Rule 21. NAVAL OPERATIONS

21. NAVAL OPERATIONS 21.1 BASING
21.2 MOVEMENT
21.3 EMPLOYMENT
21.4 NAVAL ACTIVITIES DURING THE MOVEMENT PHASE
21.41 PATROLS
21.42 SEA SUPPLY, OIL SHIPMENTS AND BRP GRANTS BY SEA
21.43 SEA TRANSPORT
21.44 HARBOR ATTACKS
21.5 NAVAL ACTIVITIES DURING THE COMBAT PHASE
21.51 SEABORNE INVASIONS
21.52 SHORE BOMBARDMENT
21.53 RAIDERS
21.54 ATTACKS ON ENEMY BASES
21.55 FAST CARRIER MISSIONS
21.56 SEA SUPPLY, OIL SHIPMENTS AND BRP GRANTS BY SEA
21.6 SEA ESCORT
21.7 UNINVERTING NAVAL UNITS

21.1 BASING:
21.11 Each port or port counter on the mapboard may base up to 50 naval factors. Naval bases, indicated on the mapboard by an anchor symbol, are significant only for naval construction and air defense, and have the same basing capacity as other ports.
21.111 A hex containing two ports may base up to 100 naval factors. A two‑port hex is treated as a single port for all purposes (EXCEPTION: Air defense - 23.42).
21.112 The capacity of a port may not be voluntarily exceeded. If overstacking occurs involuntarily as a result of a failed attempt to change base during the movement phase, the excess naval units may not be used for the remainder of the player turn. The player must remedy the overstacking before the end of the redeployment phase. If he is unable to do so, excess naval units of his choice are eliminated. If overstacking occurs as a result of a failed NR, there is no opportunity to remedy the overstacking and excess naval units of his choice are eliminated.
21.113 Damaged naval units which are in the “Waiting for Repair” box of a Naval Construction Chart do not count against the basing capacity of that port.
21.114 An unlimited number of naval factors may base in a mapboard box (5).

controlled by the alliance in question (the Western Allies may not use Russian ports, and vice versa - 53.46).
fully supplied during initial supply determination of the turn in question. Ports captured during the movement and combat phases may not be used to meet range requirements until the following turn, even if supplied during post-combat supply determination.
operational.
the capacity of jungle/mountain ports (Port Moresby, Sandakan) to meet range restrictions is limited to five hexes (21.3617).

D. MAPBOARD BOXES:

The U.S. Atlantic box is considered to be 16 hexes from the western edge of the European mapboard.

The U.S. Pacific box is considered to be eight hexes from the eastern edge of the Pacific mapboard.

The Indian box is considered to be eight hexes from the western edge of the Pacific mapboard. Naval activities from the Indian box must appear on the mapboard at hex CC2, where the coast of India intersects the western edge of the Pacific mapboard.

The Australia box is considered to be eight or ten hexes from the southern edge of the Pacific mapboard. Naval activities from the Australia box must appear on the mapboard at either hexes NN15, NN24 (Townsville) (eight hexes) or NN31 (Noumea) (ten hexes), on the southern edge of the Pacific mapboard.

South Africa is beyond the normal range of all naval activities (5.32). Only naval activities explicitly allowed to or from the South Africa box are permitted.

21.361 RANGE RESTRICTIONS: The range of naval activities is restricted as follows (EXCEPTION: Range restrictions do not apply to countries in theaters in which they are not at war). These limits apply to both fleets and carriers. The notional hexes off the western edge of the Atlantic mapboard and the eastern edge of the Pacific mapboard are considered to be Western Allied ports for purposes of rules 21.3611-3615.
21.3611 INTERCEPTIONS, COUNTER-INTERCEPTIONS: There is no range limit on interceptions and counter-interceptions, although the greater the distance to the interception hex, the less chance an interception or counter-interception will succeed (22.1, 22.2).
21.3612 SEA SUPPLY, NRs, SEA ESCORT: There is no range limit for sea supply (30.33), NRs and sea escort (28.5), although such activities must touch a port (21.36C) at least once every 20 (Europe) or 10 (Pacific) hexes. (EXCEPTIONS: See 21.3615 and 21.3616 for exceptions in the Pacific). Islands without port access (21.37) from which units are being NRed are considered to contain ports for the purpose of meeting the range requirement for that sea escort only.
21.3613 BASE CHANGES, NAVAL DISPLACEMENT: Base changes may not exceed 40 (Europe) or 20 (Pacific) hexes. Displaced naval units may not move more than 40 ( Europe) or 20 (Pacific) hexes. (EXCEPTION: See 21.3616 for exceptions in the Pacific).
21.3614 OFFENSIVE NAVAL MISSIONS: Offensive naval missions may not exceed 40 (Europe) or 20 (Pacific) hexes, and must touch a port (21.36C) at least once every 20 (Europe) or 10 (Pacific) hexes. (EXCEPTIONS: See 21.3615 and 21.3616 for exceptions in the Pacific). In addition, the following exceptions apply specifically to seaborne invasions:

The range of a commando unit using its special capability to invade a port is restricted to 10 ( Europe) or 5 (Pacific) hexes.
Dutch Harbor may not be used as a base for seaborne invasions.
For Japan to invade Dutch Harbor from Japan, it must control and fully supply another Aleutian island. The invasion must pass through the required island en route to Dutch Harbor.

21.3615 ALLIED RANGE EXCEPTIONS IN THE PACIFIC:
A. HAWAIIAN ISLANDS: If the Western Allies control and fully supply both Midway and Johnston Island, the initial leg of a Western Allied naval activity beginning in the Hawaiian Islands may cross up to 15 hexes before touching a port (21.36C). If the Western Allies also control and fully supply Wake, the initial leg of a Western Allied naval activity beginning in the Hawaiian Islands may cross up to 20 hexes before touching a port (21.36C).
B. ALEUTIAN ISLANDS: A Western Allied naval activity between the Hawaiian Islands and the Aleutian Islands may exceed the range limit and requires no intervening port, provided the activity proceeds by the shortest route.
C. SEA ESCORT: Ground and air units in any island within naval range of the Hawaiian Islands may be NRed back to the Hawaiian Islands, with destroyers based in the Hawaiian Islands providing sea escort.
21.3616 JAPANESE RANGE EXCEPTIONS IN THE PACIFIC:
A. JAPAN:
The initial leg of a Japanese naval activity beginning in Japan may cross up to 20 hexes before touching a port (21.36C). (EXCEPTION: Midway – 21.3616B)
B. MIDWAY, JOHNSTON ISLAND, HAWAIIAN ISLANDS:

Midway is only within range for a Japanese naval activity beginning in Japan if Japan controls and fully supplies Wake. The activity must pass through Wake and proceed by the shortest route.
Johnston Island is within range for a Japanese naval activity beginning in Japan if Japan controls and fully supplies Wake. The activity must pass through Wake and proceed by the shortest route.
Ground units used in invasions of Midway or Johnston Island originating in Japan may be in Japan or Wake.
Japanese naval activities between Japan and the Hawaiian Islands may exceed the normal range limits and require no intervening ports if Japan controls and fully supplies Wake and either Midway or Johnston Island. Naval activities must pass through the required islands and proceed by the shortest route. Specifically:
- Naval units based in Japan may patrol within three hexes of a Hawaiian Island.
- Naval units based in Japan may be used to invade or shore bombard a Hawaiian Island; the ground units used in such an invasion must be in Japan, Wake, Midway or Johnston Island.

C. ALEUTIAN ISLANDS: Japanese naval activities between Japan and the Aleutian Islands may exceed the normal range limits and require no intervening port, provided the activity proceeds by the shortest route.
D. INITIAL ATTACK ON PEARL HARBOR: The patrol mission for the initial Japanese attack on Pearl Harbor (51.12) may exceed the range limit and need not touch a port every 10 hexes.
E. SEA ESCORT: Ground and air units in any island within naval range of Japan may be NRed back to Japan, with destroyers based in Japan providing sea escort.
21.3617 PORT MORESBY, SANDAKAN: Because Port Moresby and Sandakan are in jungle/mountain hexes, their maximum capacity for meeting the 21.36C range restrictions is five hexes. No naval operations or activities, other than interceptions and counter-interceptions by naval units based in Port Moresby or Sandakan, may originate in or pass through Port Moresby and Sandakan without terminating or passing through an eligible port no more than five hexes away.
21.362 FRONT BOUNDARIES IGNORED: Front boundaries have no effect on naval activities.
21.37 ISLANDS WITHOUT PORT ACCESS: Naval units may sea transport and NR ground and air units into and out of, and ground units may conduct seaborne invasion from, controlled islands which do not contain a port as follows:
A. One-hex islands.
B. Palawan, New Ireland and Halmahera, through their beach hexes as though they were ports (4.75).

21.4 NAVAL ACTIVITIES DURING THE MOVEMENT PHASE:
21.41 PATROLS:
21.411 OVERVIEW: During the movement phase naval units may move to an announced sea hex (the “patrol hex”) in order to attack enemy bases, assist in ground attacks and improve their chances of counter-intercepting enemy naval activities during the movement phase or the ensuing combat phase.
21.412 RANGE: Patrols are subject to the range restrictions for offensive operations set out in 21.3614.
21.413 PATROLS FROM MAPBOARD BOXES:
A. Patrols may not be conducted by naval units based in the U.S. or South Africa boxes.
B. Patrols may be conducted by naval units based in the India and Australia boxes. The India and Australia boxes are eight hexes from the western and southern edges of the Pacific mapboard, respectively.
21.414 COST AND TIMING:
A. BRP COST: Patrols are an offensive mission and BRPs must be paid for all participating naval units on the front containing the patrol hex (EXCEPTION: No BRP expenditure is required for patrols by submarines - 9.56A).
B. TIMING: Movement to patrol hexes, base changes (21.22) and SW naval deployments (25.31) are contemporaneous. Naval units may not change base during a movement phase in which they patrol. Naval units from different bases may, however, combine to carry out a joint patrol in the same hex. Naval units forming a joint patrol move to the patrol hex at the same time and may join at sea before reaching the patrol hex.
21.415 BASING: The patrol hex functions as the patrolling force’s base during the remainder of the movement phase and the ensuing combat phase. However, for basing purposes, a patrol is considered to have remained in its base of origin while on patrol. Naval units therefore may not change base into a base from which a patrol has been sent if the base did not have sufficient capacity to base both naval forces.
21.416 MECHANICS: Patrols are conducted using the following sequence:
A. The moving player announces all patrols, base changes and SW naval deployments (25.31). The moving player does not announce any air strikes by patrolling carriers at this time.
B. If the moving player is conducting more than one patrol, he designates the sequence in which his patrols will be conducted. The first patrolling force then moves toward its patrol hex along whatever route the moving player wishes (subject to the range restrictions for patrols - 21.3614).
C. When a patrolling force enters a new hex, the defending player may attempt naval interception of the patrolling force in the same manner as other naval activities. Naval interception is resolved before the patrolling force counterairs any defending air units from the new hex. Defending air units within air range of the interception hex therefore assist in any naval interception of the patrolling force (22.231A).
D. If naval interception occurs, naval combat is resolved normally. Both the intercepted patrolling force and any intercepting naval forces may counterair enemy air units within range of the interception hex as part of naval combat (22.41B).
E. If the patrolling force wins the naval combat, it may either continue moving to its patrol hex or abort its patrol and return to port, at the moving player’s option.
F. If the patrolling force loses the naval combat, it must return to port and is inverted for the remainder of the player turn. The victorious intercepting naval forces may remain in the interception hex as a defensive patrol (21.419) or return to port and invert for the remainder of the player turn, at the defender’s option.
G. If no naval interception occurs, a patrolling force containing fast carriers which has not yet arrived in its patrol hex may engage in one round of counterair combat against any enemy air bases within range of its hex:

each patrolling naval air unit may only be used to counterair one enemy base from that hex.
surviving patrolling naval air units may be used to counterair different enemy air bases once the patrol moves to a new hex. Until it reaches its patrol hex, each patrol may make only one counterair attack against each enemy air base.
defending air units which are not eliminated or forced to abort by a patrolling force's counterair attack, or which are in other bases within range of the patrolling force, remain available for use and may make one air attack against the patrolling force before it enters its next hex.
after air attacks are resolved, any submarine attacks in the hex are resolved (22.92C).

H. As a patrolling force enters each hex en route to its patrol hex, the sequence set out above is repeated.
I. Once the patrolling force reaches its patrol hex, it may launch repeated counterair attacks/air strikes against all enemy bases within range of its patrol hex.
J. Before each round of counterair attacks/air strikes from the patrol hex, the defender has the option of attempting naval interception if he has not done so previously.
K. When the moving player has finished all his counterair attacks/air strikes from the patrol hex, he announces whether his patrolling force is returning to base or remaining in the patrol hex during the combat phase.
L. If a patrolling force remains in the patrol hex, the defender may attempt interception of the patrolling force, if he has not already done so, by immediately rolling eight dice, subject to modification as set out in the Naval Interception Table (22.23), for each intercepting naval force. Any resulting naval combat is resolved. The loser returns to base and is inverted for the remainder of the player turn, and the victor has the option of returning to base and being inverted for the remainder of the player turn or remaining in the patrol hex during the ensuing combat phase.
M. Defending air units that were aborted in their final round of air combat with the patrol are inverted. If the moving player is conducting more than one patrol, steps B through M are repeated for each subsequent patrol, until all patrols are resolved.
N. Once all patrols are concluded, all base changes and SW naval deployments are completed.

Protect your naval bases with land-based air, especially in the Pacific! In a single turn a base may be counteraired before it is attacked by a patrol, attacked by two or more separate patrols (with the exception of the initial attack on Pearl Harbor), and may be bombed again in the combat phase.

21.417 INTERCEPTION OF PATROLS: A patrolling force may be intercepted:
A. En route to and in its patrol hex (21.416C, 21.416J).
B. Once all air strikes from its patrol hex are completed if it attempts to remain in its patrol hex (21.416L).
21.4171 The defender may not attempt interception of a patrolling force at one point, then attempt interception again later with the same or other naval forces except as allowed by 22.13.
21.418 OFFENSIVE PATROL FUNCTIONS: Each patrolling naval and naval air unit may be used as follows. Naval and naval air units may participate in naval combat without impairing their ability to perform these operations:
21.4181 AIR UNITS:
A. As a patrolling force moves to its patrol hex, patrolling naval air units may counterair enemy bases (21.416G).
B. Once a patrolling force reaches its patrol hex, patrolling naval air units may launch repeated counterair attacks/air strikes against all enemy bases within range of its patrol hex (21.416I).
C. Naval air units in a patrolling force which remains at sea (21.416L) may also do any one of the following:

provide ground support or intercept defensive air support in relation to an overrun during the movement phase.
conduct a counterair attack or air strike against an enemy base during the combat phase.
provide ground support or intercept defensive air support in relation to a non-exploitation attack during regular combat. Patrolling naval air units may not be used to support exploitation attacks, as their patrol must return to port prior to exploitation combat.

21.4182 NAVAL UNITS:
A. COUNTER-INTERCEPTIONS: Patrolling forces which remain at sea (21.416L) may counter-intercept only by supporting intercepted friendly naval forces (22.162).
B. SUCCESSFUL SUPPORT: A patrolling force which supports an intercepted friendly naval force joins the supported naval force and adopts its mission once any naval combat is resolved, provided it is permitted to do so.
C. UNSUCCESSFUL SUPPORT: A patrolling force which fails to reach an intercepted friendly naval force and therefore does not engage in naval combat returns to its patrol hex and may not attempt to counter-intercept again until a later phase.
D. DIVIDING A PATROL: A patrolling force may divide into smaller forces to support different intercepted friendly naval forces. Part of a patrolling force may remain uncommitted.
E. RESTRICTIONS: Since patrols are contemporaneous with other patrols, base changes and SW naval deployments, they may not directly support such naval activities by counter-intercepting. Patrolling forces may not provide shore bombardment or intercept (EXCEPTIONS: Successful support - 21.4182B, Defensive patrols - 21.419).
21.4183 RETURN TO BASE PRIOR TO EXPLOITATION: All patrolling forces return to base (21.33) and are inverted for the remainder of the player turn at the end of regular combat, prior to exploitation, after all other offensive missions are resolved, (EXCEPTION: Submarine patrols may remain at sea - 21.4184).
21.4184 SUBMARINE PATROLS: Submarines may patrol in the same manner as other naval units, subject to the same restrictions as other patrols, with the following special features:
A. Submarines patrol independent of other naval forces.
B. Submarine patrols may remain at sea when other patrols return to base. If they do not return to base (21.4183), they remain at sea until they attack, engage in naval combat, or until the end of the opposing player turn, whichever comes first.
C. Submarine patrols at sea during the opposing player turn may be attacked in a single sortie by enemy land-based air units within range of their patrol hex during the movement phase of the opposing player’s turn, immediately after counterair attacks are resolved. Air cover may be flown over the patrolling submarines, but no air defense dice roll is made by the defender. Submarines may not be attacked by enemy carrier-based naval air units or enemy fleet units.
D. A submarine patrol may counter-intercept in the same manner as other patrols (21.4182A). During the opposing player turn, a submarine on patrol is considered to be a defensive patrol (21.4195).
E. German submarines may not remain on patrol on the western front during the Allied player turn if Germany conducted submarine warfare in the Atlantic SW box during the Axis player turn.
21.419 DEFENSIVE PATROLS:
21.4191 A defending naval force which intercepts and defeats a patrolling force may, at the defender’s option, remain in the interception hex until the end of regular combat in the ensuing combat phase. The defending naval force is then considered to be on defensive patrol. A victorious defending naval force which returns to base during the movement phase is inverted for the remainder of the player turn.
21.4192 A defensive patrolling force may attempt interceptions or counter-interceptions from its patrol hex in the same manner as it would from port (22.14F). The defensive patrolling force may attempt to intercept during the sea supply or sea transport segments of the movement phase and again during the combat phase.
21.4193 The ability of a defensive patrolling force to intercept an enemy patrol, then intercept again as permitted by 21.4192, is an exception to the rule that naval units may only intercept once each turn. Only one successful 21.4192 interception is permitted each turn.
21.4194 If a defensive patrol intercepts an enemy naval activity, it may be counter‑intercepted normally in any hex along its interception route, including its patrol hex. Otherwise defensive patrols may not be counter-intercepted.
21.4195 Submarines on patrol during the opposing player turn are considered to be defensive patrols and may attempt to intercept any enemy naval activity during any turn segment, in the same manner as they would from port (22.14F).

21.42 SEA SUPPLY, OIL SHIPMENTS AND BRP GRANTS BY SEA: During initial supply determination, the moving player may conduct the following naval activities:
21.421 SEA SUPPLY:
A. SEA SUPPLY FROM PORTS: Sea supply lines from ports do not require naval units (30.331).
B. SEA SUPPLY FROM MAPBOARD BOXES: Each Western Allied sea supply line from a mapboard box requires the use of one transport in the relevant shipping area (30.365).
21.422 OIL SHIPMENTS: Oil counters may by shipped by sea. One transport (Western Allies, Japan) or three destroyer factors (European Axis) are required to sea escort each oil counter shipped by sea (20.64A, 33.43B).
21.423 BRP GRANTS: Western Allied BRPs grants may be made by sea. One Western Allied transport is required to sea escort each BRP grant of up to five BRPs (20.64D).
21.424 PROTECTION OF NAVAL ACTIVITIES: The above naval activities may be protected (21.65E, F, 30.36).

21.43 SEA TRANSPORT:
21.431 During the movement phase, destroyers may sea transport ground or air units by moving them from a controlled port, eligible island (21.37) or eligible mapboard box to another controlled port, eligible island or mapboard box.
21.432 RANGE: Sea transports are subject to the range restrictions for offensive operations set out in 21.3614.
21.433 SEA TRANSPORT TO AND FROM MAPBOARD BOXES: Sea transport is permitted:
A. Between the Atlantic U.S. box and a western front port, through the Atlantic Ocean.
B. Between the Pacific U.S. box and Dutch Harbor, the Hawaiian Islands (Hawaii, Kauai, Maui, Necker, Oahu) or the Society Islands (Bora Bora, Tahiti), through the Pacific Ocean.
C. Between the India and Australia boxes and the Pacific mapboard.
D. Between the India box and Suez, Basra or Abadan, through the Indian Ocean.
E. Between the Australia box and Suez, Basra or Abadan, through the Indian Ocean.
F. Between the South Africa box and Suez, Basra or Abadan, through the Indian Ocean.
21.434 DESTROYER AND TRANSPORT REQUIREMENTS:
A. One destroyer factor is required to sea transport each ground or air factor, except as set out below.
B. Two destroyer factors are required for each ground or air factor sea transported to or from the U.S., South Africa, India and Australia boxes.
C. Sea transport to or from a mapboard box also requires one transport from the SW box through which the sea transport passes for every five ground or air factors sea transported (20.64C).
21.435 MECHANICS:
A. Destroyers used to sea transport need not be based at the base of embarkation.
B. Destroyers used to sea transport may move from their base to the base of embarkation, then to the base of debarkation, subject to range restrictions (21.3614).
C. There may be more than one base of embarkation for one sea transport mission; but there may be only one base of debarkation. Different bases of debarkation require independent missions.
D. Both the base of embarkation and debarkation must have been under friendly control at the start of the transporting player’s player turn.
E. Other naval units may accompany destroyers conducting sea transport in order to protect the sea transport mission. Such naval units are subject to the same basing and movement restrictions as the destroyers conducting the sea transport.
F. Sea transport may not be used to land forces on a bridgehead counter unless the bridgehead hex also contains a port (EXCEPTION: One- and two-hex islands without port access - 21.37).
G. A unit may not be sea transported from one location to another, then sea transported again from the new location, in the same turn.
H. Units which are sea transported debark during the movement phase and are subject to stacking limitations at the end of the movement phase.
21.436 UNSUCCESSFUL SEA TRANSPORTS:
A. Naval units on a sea transport mission which are intercepted and abort their mission or withdraw from naval combat before arriving at the base of embarkation return to their original base.
B. If interception and defeat in naval combat occurs after the embarkation of the transported ground or air units, but before debarkation at the intended destination, the naval units on the sea transport mission and the surviving units they are carrying return to the base of embarkation, the transported units debark, and the naval units return to their original base.
C. Subject to the normal rules of supply, ground units which return to their base of embarkation incur the usual movement factor cost for debarking (21.437), but otherwise may move and conduct attacks, and air units may fly missions from the base of debarkation.
21.437 SEA TRANSPORT OF GROUND UNITS:
A. MOVEMENT: Ground units may use their full movement capability during the player turn in which they are sea transported. Ground units may move to the port of embarkation before being sea transported, prior to the movement of other ground units, but may not conduct overruns as they do so. Only ground units which have sufficient movement factors to meet the costs of embarkation (if any) and debarkation may be sea transported. Ground units may move after being sea transported, if permitted by their remaining movement factors, and may engage in overruns, offensive ground attacks or attrition in conjunction with other ground units .

There is no movement cost to embark (EXCEPTION: If the port of embarkation is in an enemy ZoC, there is a movement cost of two movement factors in Europe and one movement factor in the Pacific to embark, even if the ground unit and the transporting fleet begin the turn in the port of embarkation).
There is a movement cost of one movement factor to debark, plus an additional movement factor if the port of debarkation contains rough terrain (EXCEPTIONS: Japanese ground units and the Chindit entering jungle hexes do not incur an additional movement cost - 13.41C). There is no additional movement cost to debark in a hex in an enemy ZoC.

B. STACKING: The number of ground units which may sea transport from or to a single port is not limited by stacking limits.
C. SUPPLY: Ground units which are partially supplied or subject to an army oil effect may not be sea transported.
D. INVASIONS PROHIBITED: Ground units which are sea transported may not be used to invade in the same turn.
21.438 SEA TRANSPORT OF AIR UNITS:
A. BASING: The air unit must begin the player turn in the base of embarkation. The base of debarkation is treated as the air unit’s new base. A sea transport is the equivalent of staging: a sea transported air unit may not stage to the base of embarkation or from the base of debarkation. Inverted air units may be sea transported.
B. STACKING: The transportation of air units is prohibited if the transportation would result in too many air factors in the base of debarkation.
C. OPERATION: Air units which have been sea transported may operate normally during the ensuing combat phase. There is no reduction in range to reflect the movement cost of debarking, which only applies to ground units.

21.44 HARBOR ATTACKS:
21.441 TIMING: Harbor attacks are resolved by the moving player during the movement phase, after attacks from patrols are completed, but prior to the completion of base changes and the movement of naval units to and from SW boxes.
21.442 HARBOR ATTACK RESULT REQUIRED: To carry out a harbor attack, the moving player must have achieved the required research result (EXCEPTION: The initial German harbor attack - 21.444).
21.443 MECHANICS: Harbor attacks are resolved using the Harbor Attack Table (see the Research Tables and Player Aids). When a harbor attack is made, the following sequence is followed:
A. The attacker announces the target hex, the nature of the attack and all his applicable modifiers.
B. The defender announces all his applicable modifiers, including the application of a counter-intelligence result.
C. Both players may play tactical cards in an attempt to gain a codebreaking advantage (48.32B).
D. The harbor attack is resolved.
21.444 INITIAL GERMAN HARBOR ATTACK: Germany begins the game with the ability to make a harbor attack against one enemy target. This attack may be made in Fall 1939 or any subsequent turn, provided no other harbor attacks have been made. The execution of this attack does not modify subsequent harbor attacks.

21.5 NAVAL ACTIVITIES DURING THE COMBAT PHASE:
21.51 SEABORNE INVASIONS:
21.511 OVERVIEW: During the combat phase, ground units in a controlled port, eligible island or eligible mapboard box may be carried by destroyers and invade an eligible invasion hex (21.5154).
21.512 RANGE: Seaborne invasions are subject to the range restrictions for offensive operations set out in 21.3614. In addition, the following exceptions apply:
A. COMMANDOS: The range of a commando unit using its special capability to invade a port is restricted to 10 ( Europe) or 5 (Pacific) hexes.
B. DUTCH HARBOR: Dutch Harbor may not be used as a base for seaborne invasions.
C. ALEUTIANS: For Japan to invade Dutch Harbor from Japan, it must control and fully supply another Aleutian island. The invasion must pass through the required island en route to Dutch Harbor.
D. PERMITTED MAPBOARD BOX INVASIONS: Seaborne invasions are permitted:

from the Atlantic U.S. box into an eligible western front hex or Gibraltar, through the Atlantic Ocean.
from the Pacific U.S. box into Dutch Harbor, the Hawaiian Islands (Hawaii, Kauai, Maui, Necker, Oahu) or the Society Islands (Bora Bora, Tahiti), through the Pacific Ocean.
from the India and Australia boxes onto the Pacific mapboard.

E. PROHIBITED MAPBOARD BOX INVASIONS: Seaborne invasions from the South Africa box or into a mapboard box are prohibited.
21.513 DESTROYER AND TRANSPORT REQUIREMENTS:
A. UNDEFENDED HEXES: One destroyer factor is required to carry each invading ground factor if the invasion hex is not occupied by an enemy ground unit.
B. DEFENDED HEXES: Two destroyer factors are required to carry each invading ground factor, including ground units which do not participate in the initial invasion combat, if the invasion hex is occupied by an enemy ground unit.
C. INVASIONS FROM MAPBOARD BOXES:

One additional destroyer per ground factor is required for invasions from the U.S., Indian and Australia boxes.
One Western Allied transport in the relevant SW box is required for every five Western Allied ground factors which invade from the U.S., Indian and Australia boxes.

the Atlantic SW box is considered to be on the western front.
the Indian Ocean SW box is considered to be on the Mediterranean (Suez) or Southeast Asian (Colombo, Madras or Singapore) front.
the Pacific SW box is considered to be on the Pacific front.

21.532 RAIDER GROUPS:
A. ELIGIBLE SHIPS: Cruisers, capital ships and fast carriers may raid; Japanese five-factor battleships, destroyers and slow ships may not.
B. ATLANTIC SW BOX: Only German naval units based in a western front port may raid into the Atlantic.
C. INDIAN OCEAN SW BOX: Up to three German or Italian ships may raid from Suez if the Axis control the Suez canal and Ethiopia. Up to three Japanese ships may raid from each of Colombo, Madras and Singapore.
D. PACIFIC SW BOX: Japanese ships may raid into the Pacific SW box from Townsville, Noumea, Suva, or any port in the Hawaiian Islands. Up to three Japanese ships may raid from each such port.
E. COMPOSITION: Each raider group may consist of no more than three ships, no more than one of which may be a fast carrier. Each two-factor cruiser is considered one ship.
21.533 MOVING TO AN SW BOX:
A. RAIDS FROM DIFFERENT PORTS: More than one raider group may raid from a single port. Ships based in different ports may rendezvous in a hex and form a raider group prior to entering an SW box.
B. MOVEMENT OF RAIDERS TO SW BOXES: Raiders must move from port to the SW box before they may attack enemy transports (EXCEPTION: 21.5331). Raider groups may not travel together for mutual support (22.141).
C. PRIORITY: If more than one raider group attempts to raid in the same SW box, the raiding player must designate one raiding group as the first raider, another as the second raider, and so on. If the European Axis and Japanese both raid in the Indian Ocean and cannot agree, the Japanese decide the order of raiding groups. The first raiding group is less likely to be intercepted (see the Raider Table - 21.5342).
D. ON-BOARD INTERCEPTION: Raiders may be attacked by air or intercepted on the board while moving to an SW box. If the raider defeats the on-board air attacks or interception and enters the SW box, it may be engaged in the SW box (21.534). Naval units raiding from Bergen or Scapa Flow move directly to the Atlantic SW box and are not subject to air attack or on-board interception as they do so.

One die is used to intercept raiders, minus one die if the raider group consists of fewer than 10 naval factors (22.232D). It follows that normally a raider may only be intercepted on the board if a favorable interception modifier for friendly air units or codebreaking applies, or if the raider passes through a hex in which enemy naval units are based (22.242).

21.5331 PLACEMENT OF RAIDERS DURING OPENING SETUP: Germany may place one or more of the Graf Spee, Lutzow or Scheer in the Atlantic SW box during its opening setup. These may be grouped together or in separate raiding groups. Once placed, these ships must raid, with Germany paying one BRP for each raiding ship during its Fall 1939 combat phase.
21.534 DEFENDING AGAINST RAIDERS IN AN SW BOX:
21.5341 FIRST ENGAGEMENT ATTEMPT: After the defender has resolved any naval interceptions of the moving player's other naval missions, the defender may roll one die for each raider group and consult the Raider Table to determine how many defending ships engage each raiding group. The defender may choose not to oppose a raiding group, but once the defender has decided to oppose a raider group, he cannot change his mind.
A. If the modified die roll for a raider group is “0” or less, the raider group escapes detection and may attack the defending transports (21.5361A).
B. If the modified die roll for a raider group is “1”, the raider group is engaged by a two-factor cruiser.
C. If the modified die roll for a raider group is “2” or more, the raider group is engaged by a two or more defending ships, the first being a cruiser (“2” = two ships, including the cruiser; “3” = three ships, including the cruiser; etc.).
21.5342 DETERMINING WHICH SHIPS ENGAGE:
A. Defending ships must be uninverted in one of the following locations. All uninverted defending ships in the listed locations are eligible, and in some circumstances may be required, to engage raiding groups (EXCEPTION: Defending ships in ports which are not operational may not engage raiding groups).

ATLANTIC: The Atlantic SW box, a western front port or the Atlantic U.S. box.
INDIAN OCEAN: The Indian Ocean SW box, Suez , Basra, Abadan, Colombo, Madras or the South Africa, Australia or India boxes.
PACIFIC: The Pacific SW box, the Pacific U.S. or Australia boxes, Townsville, Noumea, Suva, Papeete, Pearl Harbor or any American port constructed in the Hawaiian Islands .

B. If there is no eligible ship of the type permitted by one of the defender’s die rolls, the number of defending ships which engage that raider is reduced accordingly.
C. If a ship is eligible to engage more than one raider group, the defender chooses which raider group to engage with that ship.
D. The first defending ship to engage a raider group is a cruiser (21.5341B).
E. For each raiding group for which the modified die roll was “2” or greater, the defender then rolls a number of dice equal to the number of additional ships which may engage that raiding group and consults the Raider Table to determine which other types of ships engage the raider. The defender must abide by the results of these dice rolls and may not refuse to send out ships against raiders.
F. No more than one fast carrier may engage a raider group in each engagement attempt, for a maximum of one fast carrier in the first engagement and a second fast carrier in the second engagement.
G. Once the defender determines the types of ships which engage all raiding groups, the defender chooses which eligible ships actually engage in naval combat with the raiders.
H. Naval units which engage raiders are not subject to attack by land-based enemy air units or interception by enemy naval units as they move to a SW box.

Raider Table - 21.5342
*One die is rolled for each raider group to determine how many defending naval units are able to engage that raider group. The die roll is modified as follows:*
*General modifiers:*
-3	Automatic
+1	for each additional raider group operating in the SW box (+1 for the second group, +2 for the third group, etc.)
+1	if the raider group contains three ships
+1	for each defender air range research result
Additional Atlantic modifiers:
+1	the U.S. is at war with Germany
+1	for every 6 CVEs in the Atlantic SW box (round down): 0-5: 0; 6-11: +1; 12-17: +2; 18-23: +3; 24+: +4
Additional Indian Ocean modifier:
+1	Japanese raiders based in Singapore.
+1	for every 3 CVEs in the Indian Ocean SW box (round down): 0-2: 0; 3-5: +1; 6-8: +2; 9-11: +3; 12+: +4. Each operational search AAS and NAS in the India box is equivalent to one CVE.
Additional Pacific modifier:
+1	for every 3 CVEs in the Pacific SW box (round down): 0-2: 0; 3-5: +1; 6-8: +2; 9-11: +3; 12+: +4. Each operational search AAS and NAS in the Australia box is equivalent to one CVE with respect to Japanese raiders entering the Pacific SW box off the southern edge of the Pacific mapboard (only).
Additional modifier for German and Italian raiders:
+/-1	Ultra codebreaking advantage
Additional modifier for Japanese raiders:
+/-1	Magic codebreaking advantage
Modified results of “1” or greater permit defending ships to engage the raider group in question.
The first defending ship to engage is always a cruiser. The type of additional defending ships which engage each raiding group is determined by rolling one die. If no ship of the required type is available, substitutions are not permitted:
1	Cruiser
2	Cruiser or 2-factor battlecruiser
3	3-factor battleship or battlecruiser
4	4-factor battleship
5	5-factor battleship or a fast carrier
6	Defender’s choice of any eligible ship

It's easy to determine what ships engage a raider. For each die roll, a cruiser or battleship equal in size to the die roll result may engage. So a "2" result allows a cruiser or a 2-factor capital ship to engage the raider. Fast ships are better for initially engaging raiders because they may remain for the second engagement (21.538B).

Western Allied sea escorts between ports on the Western front (Atlantic transports).
Western Allied sea escorts between Townsville, Port Moresby, Lae, Rabaul, Noumea, Suva, Pago Pago and any port constructed in the Solomon, New Hebrides, Fiji or Ellice Islands (Pacific transports).
Western Allied sea escorts between Colombo, Trincomalee, Madras, Calcutta, Rangoon or Singapore (Indian Ocean transports).
Japanese sea escorts between any ports or eligible island hexes (21.37) on the Pacific mapboard.

H. Transports must be used for sea escorts which:

begin or end in a mapboard box.
Western Allied sea escorts between Suez, Basra and Abadan.

I. Sea escorts using transports may be continued using destroyers based in the port where the portion of the sea escort using transports ends. Similarly, sea escorts using destroyers may be continued using transports if transports are available to sea escort from the port where the portion of the sea escort using destroyers ends.
Example: The Western Allies may sea escort a ground unit from the Atlantic U.S. box to the India box in a single redeployment, using Atlantic transports for the leg from the U.S. box to Gibraltar, DDs based in Gibraltar for the leg from Gibraltar to Suez, and Indian Ocean transports for the leg from Suez to the India box.
21.65 MECHANICS:
A. Destroyers used for sea escort must either be based in the embarkation hex or mapboard box or reach the embarkation point on the initial leg of the sea escort.
B. Transports used for sea escort may only have one base of embarkation and one destination.
C. Cargo being sea escorted must be embarked at a controlled, fully supplied port, eligible island hex (21.37) or mapboard box.
D. Cargo being sea escorted must be debarked at a controlled, partially or fully supplied port, eligible island hex (21.37) or mapboard box or, for oil shipments, a beachhead placed by seaborne invasion.
E. Oil counters and BRP grants may be sea escorted to a destination that is not yet supplied at the same time post-combat supply is traced to the destination. If the supply line is cut, the oil shipments and BRP grants are aborted.
F. Other naval units may accompany sea escorts in order to protect the sea escort. Such naval units are subject to the same basing and movement restrictions as destroyers conducting sea escort.
G. Units, oil counters and BRPs sea escorted by transports may also be protected by naval units based in the SW box containing the transports. If more than one such transport is being used to sea escort units, the sea escorting player must indicate which naval units in the SW box are protecting which sea escort before enemy air or naval attacks on the sea escort are attempted. The use of naval units in an SW box for the protection of sea escort does not affect their ability to perform other functions in that SW box (25.36).
H. Ground and air units being sea escorted must either be in or be able to redeploy by land or air to the port or eligible island hex (21.37) from which they are being sea escorted.
I. Sea escorts to different destinations are carried out separately, as are sea escorts and NRs (28.32). Contemporaneous sea supply, oil shipments and BRP grants by sea to the same destination may be combined for mutual protection.
EXAMPLE: An American 3-2 infantry unit is in Port Moresby. The Allied player wishes to use destroyers to NR the 3-2 infantry unit from Port Moresby to the Philippines. At least three Allied destroyer factors are required for sea escort. These destroyers could not be based in the Philippines at the start of the redeployment phase. If they were, they could NR to Port Moresby, but could not provide sea escort for the 3-2 infantry unit in Port Moresby until the following turn. Planning ahead, the Allied player might have moved the required destroyers to a port within 10 hexes of Port Moresby during the movement phase, then used them for sea escort that same turn.
If Japanese naval units intercepted the sea escort of the 3-2 infantry unit from Port Moresby, and won the resulting naval combat, the 3-2 would return to Port Moresby, unless the Allies had fewer than three surviving destroyer factors, in which case, regardless of who won the naval combat, the 3-2 infantry unit would be eliminated.
21.66 UNSUCCESSFUL SEA ESCORTS:
A. Naval units used for sea escort which are intercepted and abort their mission or withdraw from naval combat before arriving at the base of embarkation return to their original base.
B. If interception and defeat in naval combat occurs after the embarkation of the sea escorted ground or air units, oil counters or BRP grants, but before debarkation at the intended destination, the naval units used for sea escort and their surviving cargo return to the base of embarkation, the cargo debarks, and the naval units return to their original base.
C. If the number of destroyer factors used for sea escort drops below the number required as a result of enemy action, the cargo being sea escorted is eliminated. If a transport used for sea escort is eliminated, the cargo being sea escorted is eliminated (22.82).
D. Ground and air units which return to their base of embarkation may SR and TR from that base.

21.7 UNINVERTING NAVAL UNITS:
21.71 UNINVERSION LIMITS: The ability to uninvert naval units is directly related to the number of oil counters assigned to naval purposes. See 33.7 for the relationship between oil consumption and uninversion capacity, restrictions on uninversion and exemptions from uninversion limits.