51. PEARL HARBOR AND ALLIED UNPREPAREDNESS
51.1 PEARL HARBOR
51.2 THE U.S. NAVY
51.3 THE INITIAL AIR STRIKE ON PEARL HARBOR
51.4 THE SECOND AIR STRIKE ON PEARL HARBOR
51.5 THIRD AIR STRIKE PROHIBITED
51.6 AMERICAN NAVAL DISPOSITIONS AFTER PEARL HARBOR
51.7 ALLIED UNPREPAREDNESS

51.1 PEARL HARBOR:
51.11 HISTORICAL SIGNIFICANCE: The Japanese attack on Pearl Harbor on December 7, 1941, was a momentous event which transformed the world political situation. There is still debate as to whether it had any real impact on the strategic situation in the Pacific, especially since the American carriers were not in Pearl Harbor when the attack occurred.
51.12 JAPANESE STRIKE FORCE: As the first patrol mission of the turn in which Japan declares war on the U.S., Japan may attack Pearl Harbor by air with a naval force consisting of any number of CVs and CVBs, plus at least two fast three-factor battlecruisers and one cruiser, without regard for the normal range limit on patrols (21.3614, 21.3616). CVLs may not be used for the initial attack on Pearl Harbor. The Japanese strike force sails as a single TF, despite its size (20.162A) and composition (20.162F), and may attack no other bases.
51.13 IMMEDIATE INVASION PROHIBITED: A Japanese invasion of Pearl Harbor on the first turn of the war is prohibited (21.3614, 21.3616).

51.2 THE U.S. NAVY:
51.21 INITIAL THEATER ALLOCATIONS: All American naval units available in Fall 1939 begin the game in either the Pacific or Atlantic U.S. boxes:
A. PACIFIC FLEET: The Pacific Fleet consists of the Enterprise (CV), Saratoga (CV), Lexington (CV), Arizona (3), California (3), Maryland (3), Nevada (3), Oklahoma (3), Pennsylvania (3), Tennessee (3), West Virginia (3), CA14, DD12.
B. ATLANTIC FLEET: The Atlantic fleet consists of the Yorktown (CV), Colorado (3), Idaho (3), Mississippi (3), New Mexico (3), New York (3), Texas (3), CA14, DD6.
C. ADDITIONAL SHIPS: Additional ships are assigned to either the Pacific or Atlantic fleet (51.244).

In classic A World at War, the only additional ships are those launched by the U.S. once A World at War has begun.

51.22 RESTRICTIONS ON PREWAR DEPLOYMENTS:
51.221 ATLANTIC FLEET RESTRICTIONS:
A. The six 3-factor battleships, 14 cruiser factors and 6 destroyer factors that form the core of the U.S. Atlantic fleet must remain in the European theater until the U.S. is at war with Japan. American naval units lost to enemy action in the European theater are considered to have remained in the European theater.
B. The Yorktown and American naval units launched in the Atlantic after the start of the game may be assigned to the Pacific fleet in Pearl Harbor, but may not be transferred to the India or Australia boxes or to any location on the Pacific mapboard other than Pearl Harbor until the USJT level reaches 45 or the U.S. is at war with Japan.
51.222 PACIFIC FLEET RESTRICTIONS: American naval units which have been assigned to the Pacific fleet may not be transferred to the Atlantic fleet until war breaks out between the U.S. and Japan.
51.223 FORMATION OF CARRIER TFs: Each American fast carrier assigned to the Pacific fleet must form a TF consisting of one operational fast carrier and enough fleet factors to create a 10-factor TF. Between six and eight fleet factors will be required, depending on whether the fast carrier is a CVL, CV or CVB. These carrier TFs may contain no more than ten naval factors, must each contain one fast carrier and, in addition to light ships, may contain no more than one four-factor battleship. Three-factor battleships may not be assigned to these American fast carrier TFs. If there are not enough TF markers, four-factor battleships or light ships available to create the required TFs, new fast carriers must be assigned to the Atlantic fleet.
51.224 ADDITIONAL NAVAL UNITS:
A. Additional American ships, apart from the starting Pacific and Atlantic fleets (51.21A, B) are assigned to either the Pacific or Atlantic fleet: B. Additional ships assigned to the Atlantic fleet may be transferred to the Pacific fleet in a later turn, prior to the outbreak of war between the U.S. and Japan. Additional ships assigned to the Pacific fleet must remain with the Pacific fleet until war breaks out between the U.S. and Japan (51.222).
C. Additional ships assigned to the Pacific Fleet base in either the Pacific U.S. box or Pearl Harbor, depending on the location of the Pacific fleet.

In classic A World at War, the only additional ships are those launched by the U.S. once A World at War has begun. The first bullet of 51.224A therefore does not apply.

51.23 EFFECT OF TENSIONS:
51.231 Both the Pacific and Atlantic fleets must remain in their U.S. boxes unless permitted to leave by a USAT or USJT tension result.
51.232 If the USJT level is 8 or more, the U.S. must NR the Pacific fleet to Pearl Harbor. Once this is done, the Pacific fleet must remain in Pearl Harbor until the outbreak of war with Japan or until the USJT level reaches 45. All naval units assigned to the Pacific fleet are considered to be based at Pearl Harbor.
51.233 While neutral, the U.S. may construct Western Allied transports only as permitted by cash and carry (27.7322A) and lend lease (27.7322B).
51.234 If the USAT level is 25 or greater, the U.S. may deploy one ASW factor to the Atlantic SW box to be used against German submarines. If the USAT level is 35 or greater, the U.S. may deploy a second ASW factor to the Atlantic SW box to be used against German submarines.
51.235 If the USJT level is 40 or more, the U.S. may deploy one Western Allied ASW from the U.S. to the Pacific SW box each turn.

51.3 THE INITIAL AIR STRIKE ON PEARL HARBOR:
51.31 PEARL HARBOR SURPRISE TABLE: If the Pacific Fleet is based in Pearl Harbor when Japan attacks the U.S., the Pearl Harbor Surprise Table is used to determine the location of the American carriers assigned to the Pacific fleet and the modifier which applies to the Japanese surprise die roll against Pearl Harbor itself:

Pearl Harbor Surprise Table - 51.31

 

USJT Level + Magic Draw

DR

0-33

34-35

36-37

38-39

40+

2

Pearl

Pearl

Pearl

Pearl

Pacific

3

Pearl

Pearl

Pearl

Pacific

Pacific

4

Pearl

Pearl

Pacific

Pacific

Pacific

5

Pearl

Pacific

Pacific

Pacific

6

6

Pacific

Pacific

Pacific

6

5

7

Pacific

Pacific

6

5

4

8

Pacific

6

5

4

3

9

6

5

4

3

2

10

5

4

3

2

Auto

11

4

3

2

Auto

Auto

12

3

2

Auto

Auto

Auto

DRM

+6

+6

+5

+4

+3

Pearl:

Pacific:

Number:

Auto:

Carrier TF in Pearl Harbor.

Carrier TF in the Pacific U.S. box.

Distance of carrier TF from Japanese patrol hex

Interception of Japanese patrol automatic.

Explanation: Consult the appropriate column and roll two dice for each American carrier TF. The column used is determined by the USJT level at the moment Japan declares war on the U.S., less all strategic Magic cards played by Japan and plus all strategic Magic cards (secretly) applied by the U.S. in the turn in which Japan attacks (48.71).

The result indicates the location of each American carrier TF at the time of the Japanese attack. A numerical result means the American carrier TF is at sea (the larger the number, the farther the distance from the Japanese striking force).

If the Japanese striking force launches a second air strike against Pearl Harbor, the U.S. player may try to intercept it. American carrier TFs in Pearl Harbor or a U.S. box may not attempt interceptions; American carrier TFs which achieved an Auto result intercept automatically; otherwise one die is rolled for each American carrier TF. The interception attempt succeeds if the result is equal to or greater than the numerical result for that American carrier TF.

“DRM” indicates the modifier applied to the die roll made by the Japanese to determine the level of surprise achieved against Pearl Harbor in the first round of their attack.

In all cases, apart from any other modifiers, American air defense dice level is reduced by one and Japanese air attack dice rolls against enemy naval units and surprised air units receive a +1 DRM.

American air units which are surprised on the ground are attacked as naval units (One AAF and three NAS are the equivalent to one naval factor). Army and naval air units are attacked separately.

Surprise Level

Result

4

One fewer defending air squadron engages the attacking naval air.

5

Two fewer defending air squadrons engage the attacking naval air.

6

Three fewer defending air squadrons engage the attacking naval air.

7+

No defending air squadrons engage the attacking naval air. No air defense dice roll is made. All air attacks which damage a named ship trigger a critical hit die roll against the target (20.5241C).


51.311 DETERMINING WHICH COLUMN TO USE: The column used on the Pearl Harbor Surprise Table is determined by the USJT level at the moment Japan declares war on the U.S. The USJT level used to determine the applicable column is reduced by one for each strategic Magic card played by Japan and increased by one for each strategic Magic card secretly played by the U.S. in the turn in which Japan attacks. Strategic Magic cards used to modify the USJT level in relation to the Pearl Harbor attack may not be used for any other purpose.

If USJT increases from status modifiers trigger a Japanese mobilization in the turn Japan attacks the U.S., the USJT level increases by an additional one prior to the Japanese declaration of war, with possible additional increases if Japan uses the mobilization to increase its shipbuilding rate (36.11C).

51.312 AMERICAN CARRIER LOCATIONS: If the Pacific Fleet is based in Pearl Harbor when Japan attacks the U.S., the location of each American fast carrier TF in the Pacific fleet at the moment of the Japanese attack is determined by a secret roll of two dice for each fast carrier TF. The possible results are set out below. Results 51.312B-D are not revealed until the Japanese attack on Pearl Harbor, including a possible second air strike, is completed.
A. PEARL: The carrier TF is in port in Pearl Harbor and may be attacked in the initial Japanese air strike.
B. PACIFIC: The carrier TF is in the Pacific U.S. box for refitting.
C. NUMBER: A numerical result means the American carrier TF is at sea (the larger the number, the farther the distance from the Japanese striking force). This determines how likely the carrier TF is to intercept the Japanese strike force if it remains in the vicinity of Pearl Harbor to launch a second strike.
D. AUTO: The carrier force is adjacent to the patrol hex of the Japanese strike and interception is automatic if the Japanese player elects to launch a second strike against Pearl Harbor.
51.313 THE SURPRISE LEVEL OF THE PEARL HARBOR ATTACK: Once the locations of the American carrier TFs are determined, the Japanese player determines the surprise level of his initial air strike against Pearl Harbor by rolling one die, adding the modifier at the bottom of the applicable column on the Pearl Harbor Surprise Table, and consulting the surprise results on the Pearl Harbor Surprise Table. No other modifiers, including defending air factors and radar, apply to the Pearl Harbor surprise die roll.

The lower the USJT level when Japan attacks, the greater the chances that the U.S. will be unprepared at Pearl Harbor and that one or more American carriers will be caught in Pearl Harbor. But a good Magic draw by the American player, or high dice rolls when determining the American carrier TF locations, may offset the effects of a low USJT level. Whether Japan should forego shipbuilding increases or opportunities in China, or attack the U.S. prior to Winter 1941, in order to increase the likelihood of sinking American carriers is a difficult strategic question.

51.32 THE INITIAL JAPANESE AIR STRIKE: Once the American player has secretly determined the location of his carriers and the Japanese player has determined the surprise level achieved at Pearl Harbor, the Japanese player launches an air strike against Pearl Harbor.
51.33 NAVAL INTERCEPTION PROHIBITED: Naval interception of the Japanese strike force is prohibited until one air strike has been resolved. All the naval air units in the Japanese strike force are used in the initial air strike against Pearl Harbor, as there is no need for the Japanese player to hold naval air units back for combat air patrol or air strikes against American naval units at sea.
51.34 RESOLVING THE INITIAL PEARL HARBOR ATTACK: The initial Japanese air strike against Pearl Harbor is resolved normally, with the Japanese player assigning his attacking naval air units separately to any American AAF, NAS, named ships and light ships in Pearl Harbor as he wishes. Oil counters in Pearl Harbor may not be attacked in the initial Japanese air strike against Pearl Harbor.
51.35 STATUS OF AMERICAN AIR UNITS IN PEARL HARBOR: During the first Japanese air strike against Pearl Harbor, American air units in Pearl Harbor, including naval air units on carriers which are in Pearl Harbor, are uninverted and are either surprised on the ground or available to engage attacking Japanese naval air units, as determined by the Japanese surprise result at Pearl Harbor.
51.36 EFFECT OF SURPRISE ON AIR UNITS: American air units surprised in Pearl Harbor are not counteraired, but instead are subject to attack in the same manner as naval units, with a Naval Nationality DRM equal to the Western Allied Air Nationality DRM. Each Naval Attack Table result eliminates one AAF or three NAS, as the case may be. Surprised American air units in Pearl Harbor which are not eliminated by attacking Japanese naval air units engage the attacking Japanese naval air units after they have completed their initial air strike by making one air combat dice roll; the Japanese naval air units do not make an air combat dice roll against the American air units.

51.4 THE SECOND AIR STRIKE ON PEARL HARBOR:
51.41 THE SECOND JAPANESE AIR STRIKE: Once the first air strike against Pearl Harbor is resolved, the Japanese player may either withdraw his strike force or launch a second air strike against Pearl Harbor with some or all of his available naval air units.
A. If the Japanese player launches a second air strike, no surprise die roll is made and any American air units in Pearl Harbor which survived the initial Japanese air strike are available to defend Pearl Harbor.
B. A second Japanese air strike on Pearl Harbor may target any American air units, naval units or oil counters (33.424) in Pearl Harbor.
C. The Pearl Harbor oil reserve is attacked as a single target using the Naval Attack Table. No DRMs are applied to the air attack dice roll. On a “1” air attack result, one oil counter is destroyed. On a “2” air attack result, two oil counters are destroyed. On a “3” or greater air attack result, all three oil counters are destroyed.
51.42 NAVAL INTERCEPTION PERMITTED: Once the second Japanese air strike is resolved, any American carrier TFs which achieved an “Auto” or numerical result may attempt to intercept the Japanese strike force. Each American carrier TF makes a separate naval interception die roll. American carrier TFs which achieved an “Auto” result may intercept automatically. Each American carrier TF which achieved a numerical result may roll one die. The interception attempt succeeds if the result is equal to or greater than the numerical result for that American carrier TF. American naval units in Pearl Harbor or the U.S. Pacific box may not intercept the Japanese strike force. The American player is not required to attempt interception of the attacking Japanese TF.
51.43 NAVAL COMBAT RESOLUTION: If one or more American carrier TFs intercept the Japanese strike force, naval combat is resolved as follows:
A. A single round of naval combat is resolved, after which the Japanese strike force must withdraw.
B. Japanese naval air units used for a second strike against Pearl Harbor are not available for defensive operations against the intercepting American carrier TFs. Up to one-third of the Japanese NAS may be held back to fly CAP.
C. Each American carrier TF is considered to form a separate combat group.
D. The U.S. is deemed to have found the Japanese strike force. Japan is deemed to have failed to find any of the American combat groups. No search rolls are actually made.
E. The American combat groups then make one air strike with a maximum strength of 10 NAS (23.73A). A surprise roll (23.7413) is made prior to the resolution of the American air strike, after which the naval combat ends and the Japanese strike force returns to base. No fleet combat occurs.

The first difficult decision of the war for the Japanese! Genda, the genius behind the Pearl Harbor attack, understood the true spirit of the operation and urged a second strike, but Admiral Nagumo erred on the side of caution by withdrawing the Japanese strike force in order to preserve it intact for future operations. If the Japanese catch some American carriers at Pearl Harbor, or if the American player has deliberately kept some carriers in the Atlantic, a second strike requires little courage; but if several American carrier TFs are at large, the character of the Japanese player will quickly become apparent.


51.5 THIRD AIR STRIKE PROHIBITED:
51.51 ONLY TWO AIR STRIKES ALLOWED: Japan may make no more than two air strikes against Pearl Harbor in the first turn it attacks the U.S.
51.52 RETURN TO BASE: After all Pearl Harbor related air and naval combat is resolved, all surviving attacking Japanese naval units in the Pearl Harbor strike force return together to Japan and are inverted.

51.6 AMERICAN NAVAL DISPOSITIONS AFTER PEARL HARBOR:
51.61 DURING THE JAPANESE TURN: Once the Japanese striking force has returned to base, all surviving American carrier TFs which were not caught in Pearl Harbor are placed in the Pacific U.S. box (a "Pacific" result), or Pearl Harbor (a numbered or "Auto" result). Undamaged American naval units in Pearl Harbor and American carrier TFs in Pearl Harbor which did not intercept the Japanese striking force in naval combat may attempt to intercept Japanese invasions of Midway and Johnston Islands or subsequent Japanese NRs to those islands.

51.7 ALLIED UNPREPAREDNESS:
51.71 JAPANESE SURPRISE EFFECTS: The initial Japanese onslaught in December 1941 achieved complete strategic and tactical surprise, despite many indications that a Japanese attack was imminent. This Allied misjudgment of Japanese intentions and capabilities was a significant factor in Japan's early successes.
A. The following effects apply in the Pacific theater during the game turn in which Japan declares war on Britain, or on both Britain and the U.S., provided the effective USJT level has not reached 40 or more at the moment Japan declares war.
B. If the U.S. declares war on Japan, or if the effective USJT level is 40 or more when Japan declares war, the Japanese lose the advantage of surprise and these rules do not apply.
C. If Japan declares war on either Britain or the U.S., the USJT level for Pearl Harbor and surprise effects is determined at the time of the Japanese declaration of war, after USJT increases at the start of the game turn are taken into account. A final die roll to modify the actual USJT level is made immediately after the Japanese declaration of war, and the resulting effective USJT level is used to determine Pearl Harbor and surprise effects (49.852A).
D. Magic is not taken into account in determining the effective USJT level for Japanese surprise effects, although strategic Magic cards may affect the Japanese attack on Pearl Harbor (51.311).
51.72 SURPRISE EFFECTS DURING THE JAPANESE PLAYER TURN:
A. GROUND UNITS: All Western Allied and Dutch infantry and replacement units are subject to a -1 DM. This does not apply to Western Allied armor and specialized units or to Nationalist and Communist Chinese units.
B. AIR UNITS: Western Allied and Dutch air units are uninverted and defend normally (EXCEPTION: American air units surprised in Pearl Harbor - 51.36).
C. NAVAL UNITS: British, Australian and Dutch naval units may intercept Japanese naval activities normally. American submarines are inverted. For American naval units which survive the Pearl Harbor attack, see 51.61.
D. SEA TRANSPORT: All Japanese units, including armor and air units, may sea transport to a port up to 20 (Pacific) hexes from their hex of origin (21.3614A, B). Japanese ground units which sea transport do not incur the basic movement cost for debarking, although they must use a movement factor to debark in hexes containing mountain, jungle/mountain or swamp.
E. INVASIONS: All Japanese units, including armor units, may invade a hex up to 20 (Pacific) hexes from their hex of origin (21.3614B). Japanese units which invade undefended beaches may place bridgeheads and then may move, conduct overruns and attack inland, just as though they sea transported. The normal movement cost for debarking following sea transport applies to such invasions (21.437A).
F. AIR TRANSPORT: Japanese ground units which air transport do not incur the basic movement cost for debarking, although they must use a movement factor to debark in hexes containing mountain, jungle/mountain or swamp.
G. INTELLIGENCE FAILURE: American strategic Magic cards may only be used at Pearl Harbor (51.311) and may not be used for any other purpose.
H. MONSOONS: Japanese forces are not affected by monsoons.
I. COMBAT AND CTL EFFECTS: The defender may not modify the results of Japanese contested invasions or attacks against fortifications (15.55) and the CTL of Japanese armor units exploiting from seaborne invasions is not reduced (21.5183).
51.73 WESTERN ALLIED SURPRISE EFFECTS: The following restrictions do not apply to the U.S., if Japan has declared war only on Britain (50.552), or to Russia or China:
A. FIRST TURN: During the Allied player turn following a Japanese declaration of war on either Britain or the U.S:
B. SECOND TURN: During the second Allied player turn following a Japanese declaration of war on either Britain or the U.S:
51.74 LENDING CHINESE UNITS: Nationalist Chinese ground units may not operate outside China and the Flying Tigers may not be lent until the second Allied player turn after Britain and Japan go to war (52.6).