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Subject: The battle of the Coral Sea - Two Ways rss

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Robert McCoy
South Korea
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Coral Sea — Two Ways

Jim Dunnigan may have had the wrong data when he put together the Coral Sea scenario. The LAC around Port Moresby was not overwhelming or even too strong. There was a strong FTR element, but the tactical bombing capability to go with it was sadly lacking. The USAAF in Australia at this juncture could aptly be called a paper air force.

I pulled out two games on the battle of the Coral Sea and found that the land-based anti-shipping element was not anything the IJN had to worry about too much.

GDW Coral Sea (1973) 2nd edition

In the classic GDW game published in 1973 of the tactical land-based planes only 3 out of 15 have an anti-shipping capability — 3 PBYs.

And the B-17s show up intermittently and temporarily.

Avalanche Press Coral Sea (2010) 2WWAS series

In this version, the Australian P-40s are absent, but many low-quality tactical bombers are present as well as the PBYs.

The B-17s are available, but can only bomb slow-moving transports or in USN terms any ship with a movement of 2 or less.

What I have been able to gather so far:

The ratio of land aircraft (LAC) between the Allies and the Japanese was about equal. The Allies were very weak in tactical bombers however, and without carrier intervention Port Moresby was in grave danger of falling to the Japanese. Thus, stopping the Japanese was a rather desperate affair.

There was no mention in the accounts I have read so far of a multitude of Mitchells, Marauders, and A-20s continuously bombing the Japanese task force. In fact their absence from the battle reports is a common feature. What I have lately discovered is that the Allied LAC were tasked to bombing Lae and Rabaul exclusively. In their defense that is about all they were trained to do at that time. The course on precision tactical bombing would begin next month in June 42.

Original Allied Air order of battle:

Allied Order of Battle, Coral Sea

Air Forces
Naval Aircraft Points: 14 (may be divided up among the carriers in any manner within their capacity)

Land Aircraft Points:
20 LAC
(may be divided up among the Allied Air Bases in any manner within their capacity

To simplify things in USN terms, I would suggest the following changes, but choose only one:

I. Avalanche Press interpretation:
This game gives about half the fighters that the GDW game does as the RAAF with its P-40s are elsewhere guarding Darwin or Sydney. But you do get a lot of low quality bombing units that reflect early models, lack of training, and planes at the end of their life cycle that were shipped to Australia at need.

1. The allies now have only 15 LAC . And 15 LAC is about right when compared to the NAC available on the carriers.

2. The LBAC may only bomb naval units with a speed of 2 or less, think Transport units.

II. GDW interpretation:
The allies have lots of fighters with no bombing factors. 3 PBYs which are given a high rating represent the entire non-carrier tactical naval bombardment capability of the Allies. Perhaps the PBYs represent more than just their own models, but that's hard to say.

1. The 20 LAC remain as is, but only half the LAC available (rfd) may be committed to an aerial bombardment mission of any type per mutual strike phase. This means if the Allies have only 15 LAC available (5 have been shot down in previous phases), then only 7 can perform a bombardment mission in the upcoming mutual air-strike phase. This in no way limits CAP or strafing missions. The perceptive observer will note that this gives Allied LAC a maximum of 85 bombardment factors for naval attacks; this is generous. As Marc Miller points out, 'the USAAF had little to spare for the Navy in Coral Sea.'

(rfd) = round fractions down.
bombardment mission = Bomb Air or naval base, both types of ground support and bombing of land or naval units.

2. Only 3 LBAC are available at the beginning of each turn, and any shot down are replaced at the beginning of the second turn. Of course any LBAC shot down still count for vp purposes. Otherwise, treat as per the regular rules.

III. Important: For both rules modifications above.

Allied LAC had a surfeit of problems when it came to anti-shipping missions. Each time an Allied LAC attempts a naval bombing mission on chart #3 +1 to the die roll. This penalty has no effect on results on chart #5.

Use the original CAP battle rules so LBAC, LAC and NAC are fired on separately by defending CAP as each group executes its mission for each naval target bombardment mission.

Consider Lae to have a land unit in it, so the Allies cannot trace supply through it if using the original rules. Port Moresby can be isolated, but it's not easy, and there are risks. (I posted a note on supply dichotomy for those interested.)

Order of Battle Addition: Noumea (899) and Brisbane (698) have a 6-2 CDU. In addition both have 5 LAC, but these cannot transfer to another base during the game. This is just in case the Allied fleet has to run and hide, and the Japanese follow.

IV. Optional VPs.

Japanese transports were really valuable at this point of the war, so each hit on them generates double VPs. Thus a Japanese Transport is worth 40 vps when calculating for damage.

Optional: Randomizing Naval Targets (Amateur night in Pacific Battles)

There is a 50% chance a player may not choose the naval counter his mission will bomb. On an odd die roll when an Air-naval bombardment mission is executed and assuming more than one target is available, a target is chosen at random. Thus each possible ship counter is given a number(s), a die is rolled and that ship becomes the target for that particular bombardment mission be it LBAC, LAC or NAC. This is done before flak is fired, but after the mission has undergone CAP. (or put the counters in a cup and draw one, but the ships must go back in their initial flak pairing.) If using the Avalanche version, LBAC automatically miss if attempting to bomb any naval unit other than a transport when using this rule.

This optional rule represents poor intelligence, lack of coordination, and misidentification that was a prevalent feature of this battle for both sides. As players can surmise, its use may lead to unusual results.

Player's notes:

Allies: be wary of those Japanese LACs. The Japanese player may sacrifice them mercilessly to sink one of your CVs. Take advantage of small targets if the Japanese attempt to isolate Port Moresby. The LBAC flying defensive support could be the flyboys who save the day.

Japanese: remember to be cautious as you head towards Port Moresby, the Allies may get the drop on you if using the spotting rules (Diffenderfer & Love). And too many LAC losses could lead to the Allies holding onto Port Moresby which is still fairly hard to take even with a downgraded Allied LAC force.


It was fun to research this battle, and I discovered a plane type I was previously unaware of existed, 'the Douglas Banshee A-24' which was the USAAF version of the Douglas Dauntless SBD. I would not recommend trying to fly one.

The file below appears to be a summary and logbook produced by the RAAF during the Battle of the Coral Sea. Though not authenticated, its internal coherence lends to its credibility. It allayed my reservations that I had been too severe in downgrading the Allied Air force LAC capabilities at this time.
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Tony Doran
United States
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What a very cool session report. Thanks for all your hard work to give us a better historical ob.
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Robert McCoy
South Korea
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Coral Sea Two Ways

Playtest 4 - Avalanche version

Allied Air Force: 15 LAC, 5LBAC and 14 NAC (on carriers). LBAC may only bomb Transports. LAC + 1 to die roll when attempting naval bombardment on chart #3. Other capabilities not affected.

Used alternate air-to-air system — see posting on Discussion on USN air system and some suggestions under USND variants

Used alternate air-to-sea combat system. — to be posted later.

Used modified supply system — see note on supply dichotomy.

Used Randomized naval target option. — see scenario options above.

Used Love and Diffenderfer's spotting system

Pre-game: Japanese subs are on station at hexes 694 and 660, chosen randomly and placed face down, so I didn't know which was a dummy or not.

Turn 1: Japanese Naval units rendezvous at hex 726 to form invasion task group — CV-3, CV-4, CA-1,CA-2, Tr-1, Tr-2. CL-1 remains in Rabaul. Each Japanese transport is carrying one regiment, and CL -1 is carrying the engineer regiment.

Allies respond by committing CVs and escorts to hex 729 (exactly 3 hexes south of the Japanese TF)
Allied CA-2 moves to hex 730.

Mutual air-strike spotting phase: Japanese invasion task group spotted (70% chance). However since the US task force was not in a Japanese AZOC, it had a –5 on the spotting role: 4 units (–1), 3 hexes (–2) and friendly AZOC (–2), the US TF was not spotted.

All Allied planes available are assigned to naval bombing of the Japanese Task Group. The Japanese fatalistically places his NAC on CAP (15 NAC), and assigns his 15 LAC to bomb the air base at Port Morseby.

Japanese CAP (75sp) verse allied air units (3 battles).

1 LBAC eliminated and 2 aborted; Jap NAC - no loss.

5 LAC at normal range (25 sp) and 10 LAC at extended range (20sp) for a total of 45 sp. 3 Allied LAC eliminated and 6 abort. The Allies got lucky and rolled a '1' for 4 Jap NAC eliminated and 2 aborted. The 6 aborted LAC at extended range immediately returned to Cooktown and Coen. The Japanese placed 1 NAC in each of his fleet CVs.

14 allied NAC at extended range now fire on the 28 table, and the Japanese CAP is reduced to 45 sp. Both players abort 2 and eliminate 2 NAC units. Again the Allied player got very lucky.

Bombing runs:

LBAC locate target, flak has no effect, but they miss.
LAC roll for random target, but get a CV anyway. 1 LAC is eliminated and 1 aborts from flak fire. The remaining 4 LAC with 34 factors miss the CV at 17 to 1.
NAC find target. 2 are eliminated and 1 aborts from flak fire. 7 LAC bomb at 77 sp roll on the highest table at 36 to 1 or better and sink Japanese CV-3.

Japanese Port Morseby raid.
There is no CAP over the base. Flak fire misses. The Japanese attack the base at 21 to 1. 10 damage is rolled and the base is neutralized. 1 Allied LAC that was aborted from the air-naval battle is eliminated.

All planes remaining aloft now return to base. The 4 Allied LAC at normal range must return to Port Moresby.

In a normal campaign game of longer duration, it should be noted the Japanese player would probably withdraw at this point. But this is a playtest, so I will see where things lead.

2nd land and naval movement turn 1:

The US CV TF moves to hex 661. A Japanese Sub on station in 694 fires at a CV, but there is no result. CA-2 deploys to hex 696.

The Japanese Task Group moves to Port Moresby (659). CL-1 moves to 694 and debarks the engineer regt.

Japanese Inf regt in Lae moves to hex (658). Port Moresby is now out of supply. (I changed my suggested supply rule that overland supply routes cannot trace through mountain hexsides unless tracing to a port. — see note on supply dichotomy.)

Turn 1 — 2nd mutual strike phase and Japanese land attacks.

Japanese debark their land units at the beginning of the mutual strike phase in order to perform an amphibious landing.

Both CV task forces are spotted.

Both sides must choose a priority, and it's not an easy choice.

1. Protect CVs with a strong CAP.
2. Strike the enemy CVs.
3. Support ground forces on Moresby.

Allied player decides to send his NAC into strike the remaining Japanese CV. But all the Allied LAC and LBAC are sent to give ground support at Port Moresby.

The Japanese player decides likewise to send his NAC to strike the enemy CVs.

All Japanese LAC are sent to give ground support to the amphibious attack on Port Moresby.

The US air strike of 11 NAC (77sp) misidentifies its target and attacks a Transport instead.There is no CAP over the Japanese naval units off Moresby, and the flak missed. The transport (Tran-2) survives, however, with a bad attack roll, but it still incurs 30 weeks of damage.

The 7 Japanese NAC sent to attack the the US CV also encounter no CAP defense, but lose 1 eliminated and 2 abort to flak. The remaining 28 sp attack at 14 to 1 but miss.

Air superiority battle over Morseby: Since neither side has any aircraft assigned to CAP, then this battle is fought at 50% air-to-air sps.
The Japanese are reduced from 75 to 38 (15 LAC).
The Allied player is reduced from 42 to 21 (6 LAC and 4 LBAC).
The Allies incur a loss of 2/2 and assign the losses to their LBAC units for 1 abort and 1 eliminated.
The Japanese LAC incur a loss of 1/1 for 1 eliminated and 1 abort. Flak from the air base had no effect.

This rendered a final land attack of 269 to 156 which is a 1-1; a 3 is rolled which is an attacker retreat and Port Moresby is saved this time round. — note, I will discuss the difference between the old and new land crts at the end of this session.

Port Moresby is still out of supply and the air base needs a '5' or '6' to recover from neutralization. A '3' is rolled so the Allies still cannot fly missions from this base, and the 4 LAC that remain there will be unavailable for turn 2.


Turn 2:

The cowardly CV Japanese commander calculates he has pushed his luck far enough, and orders a withdrawal of his CVs. While the Japanese CAs are ordered to fight on off Port Morseby, and getting them to leave is a difficult proposition for the Allies as a surface to surface battle is out of the question. Japanese transports ordered to exit the area, but the damaged Tran-2 is not long for this world.

Thus CA-1 and CA-2 remain at hex 659. Trans-1 goes to 726 while Trans-2 limps to 693. CV-4 and CVL-2 move at full speed to hex 756. CL-1 is ordered to hex 658 in order to help block supply and possibly relieve the infantry regiment in the hex to attack Port Morseby.

Allies move their CV TF to hex 662 and CA-2 to hex 696.

The plan is to launch an air-strike against the Japanese Cruisers to drive them off. The LBACs will go after the Transports. The only target available to the Japanese is to strafe Allied air bases. Caution should not be thrown to the wind as the Japanese CV can still come back.

First mutual strike phase:

Spotting before mutual air strike: CAs in front of Port Moresby not spotted! (20% chance). Transport 1 in hex 726 not spotted! Even the CL-1 in hex 658 is not spotted! But the hapless Trans-2 in hex 693 is spotted. This is not what I expected.

All Allied planes are launched to bomb Trans-2. Both the LBAC and LAC miss, but the NAC make no mistake and sink it.

The Japanese LAC strafed both Cooktown and Coen but there was no result.

2nd naval/land movement:

Allies send CA-1 and CA-2 to hex 658 to drive off Japanese CL-1 which withdraws to 659 Port Moresby. This puts the Japanese infantry out of supply, but more importantly, it is now the only unit in the hex blocking supply to Port Moresby which pins it.

US CVs, one now unescorted, and DD-1 remain in hex 662.

The Japanese redeploy CL-1 to hex 693 which allows the Japanese land units there to enter the Port Moresby hex which consists of 1 inf regt, 1SNLF regt and 1 eng regt - (12 sps total).

Jap Trans-1 moves to hex 792 outside of Allied LAC and NAC range.

Second mutual strike phase:

The Japanese player decided to put all his air units on ground support, ditto the Allies

Air Superiority battle at 50% sps because no CAP in hex.

Allies 59 (6 LAC, 3 LBAC and 6 NAC ext)/2 =28 sps

Japanese 70 (15 LAC)/2 = 35 sps.

Both sides inflict a 2/2 result on enemy planes. The Allies downgrade their losses to 1 LBAC eliminated and 1 LBAC aborted.

Final assault on Port Moresby:

Japan: Land units 12 sps, naval support (2 CAs) 36, and 11 LAC for 154 sps which gives a total of 202.

Allies: 1 inf reg entrenched but out of supply gives 22 sps; 6 LAC and 1 LBAC gives 119 sps, and 10 NAC gives 110 sps. This gives a total of 251 sps.

The land CRT will be on the 1-2 table. The Japanese roll a '6' for a D1.

The defending Allied infantry regiment is disentrenched and air base is now Japanese controlled but damaged.The 4 allied LAC left on the air base are destroyed.

The Allies score a decisive victory as control of the Port Moresby hex is contested by the presence of an Allied unit. Thus neither side is awarded any VPs for control of Port Moresby.

The loss of the Japanese CV in the first mutual strike phase gave the Allied player 80 VPs and sinking a transport which count double in this scenario an additional 20.

Thus Allied VPs: CV sunk – 90 vps, Trans sunk – 20 vps, 2 LAC – 2 vps, 9 NAC 9 vps: total = 112 vps.

Japanese VPs: 3 LBAC – 3 vps, 4 NAC – 2 vps, 9 LAC – 3.5 vps. total = 8.5 vps


Short discussion on differences in land tables — original edition verse deluxe:

It was at this point I discovered that in the original edition of USN Port Moresby would have fallen as a result of D1 on Land class 2 has the following effect: 'If [a land unit is] defending a base or Coastal Defense unit, and out of supply, defender is destroyed.'

On the other hand, as happened on the first turn of the above play test, all land units attacking at one to one odds would be destroyed on a '3' if using the original tables; there is no attacker retreat result in the original edition. Of course, the idea in this case is for one unit to attack at a time, so only one unit can be destroyed, and then to attack on the next turn with another unit. This renders a kind of attrition but does not guarantee success.

Both points of view have some merits, but I lean towards the original designer's dictum in this case. I would use the old gamer's house rule with bias in this case. On a d(6) the defender is eliminated on a '1' through '4' , and on a '5' or '6' the defender remains in the hex unaffected.

Note: If the Japanese had taken control of the Port Moresby hex, the game would have ended in a draw.


Note on 'Randomizing Naval Targets' Option:

In the above playtest, it would be a mistake to assume that sinking a Japanese CV is easy. In my first playtest using the Randomizing Naval Targets option, the Allied player discovered the Japanese Task Group in an identical manner. However, the LAC and NAC did not identify their targets and bombed the Transports instead. (15 weeks damage on Tran-1 and 10 weeks on Tran-2 (if you had to know) which did not slow them down, and they delivered the Japanese assault forces on the next movement segment.)

Reducing the size of your Task Group is not always a good idea. For instance the Allied player can strip the escorts from his CVs to lessen the chance of detection, but if he is caught, there will be no alternate targets to choose from, and the CVs will be attacked in any case.

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