Battle of the Atlantic (1942)
Convoys vs. U-Boats in the North Atlantic

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By Pete Pellegrino (Naval War College)

Introduction: It is summer in the North Atlantic, 1942.  Admiral Dönitz’s German U-boats are prowling the east coast of North America and the mid Atlantic shipping lanes, inflicting heavy losses on the Allied merchant fleet carrying desperately need supplies to Europe.  German submariners are calling this “The Happy Time,” as Allied defensive measures are weak and the convoys disorganized.  From January to August, 1942, Axis submarines have sunk 609 ships totaling 3.1 million tons for the loss of only 22 U-boats.

Battle Report (playtest): A convoy of eight merchants escorted by four destroyers set out from New York bound for England.  After transiting unmolested for nearly two thirds of the voyage, the SS Graham was struck by a single torpedo, cutting her speed in half.  One destroyer quickly sprinted to the spot, catching U-523B on the surface, peppering it with gunfire while a second destroyer began laying down a depth charge pattern ahead of the convoy.  At the same time the opposite side of the convoy came under torpedo attack resulting in the rapid sinking of the SS Richfield.  Another destroyer, the USS Winslow, closed on the second surfaced U-boat, U-571J, engaging her with guns.  Before U-523B could be sunk, she hit the crippled SS Graham with her deck gun, finishing off the merchant ship.  Attempting to escape, U-523B was caught in a lethal depth charge barrage and sunk, while a salvo from USS Winslow destroyed U-571J, but not before another torpedo hit the SS Evergreen

As the convoy steered to starboard, attempting to shelter the damaged SS Evergreen, four torpedoes struck the SS Lusitania, which broke in half and sank.  Destroyers HMS Reliant and USS Tyler closed on Lusitania’s attacker, U-75I, trading gun fire.  Though both destroyers suffered light damage, the Reliant was able to maneuvered and ram U-75I, sending her to the bottom.  Directly ahead of the convoy, U-123L launched a four torpedo spread, hitting both USS Winslow and the SS Anthony.  The damaged USS Winslow, joined by HMS Iron Duke turned to protect the Anthony and Evergreen.  As shells rained around U-123L, another torpedo salvo sent Winslow and Anthony to the bottom.  Though raked again by gun fire from Iron Duke, U-123L’s gun crew turned their attention to Evergreen, scoring a direct hit and starting a fire which consumed the stricken cargo vessel, just as their own submarine was ripped apart by Iron Duke’s main battery.

With only three merchant ships of the original eight reaching port, this round of the Battle of the Atlantic went to the U-boats!           

Objective:  The Allies must get their merchant ships past the waiting German U-boat wolf packs and safely deliver their cargo to England.   

Cards and Vessels:  Each Convoy player has at least one US or British destroyer and two merchants in their charge.  On the base of the ship is space for a name, a box for a letter to further identify which destroyers/merchants are under the same player control, hit counters and relevant info about movement and attack.  Click HERE  for color destroyers and merchants, and HERE for black and white silhouette versions.  Each sheet of ships is laid out to provide two destroyers and four merchants per sheet. 

 Each German U-boat player controls at least one U-boat and three ‘Ocean cards.’  U-boats are represented by cards with a U-boat number, hit counters and other info on one side and a blank ‘empty ocean’ on the other.  When submerged, the U-boat card is turned over with the blank side up.  When on the surface, the card is turned with the U-boat side up.  Ocean cards have a number and space for a letter on one side, and empty ocean on the other (In order to keep track of which ocean cards are under whose control, players should assign the same letter at the end of their U-boat designation to their ocean cards.  So one player would have control of U-234 A, Ocean 1A, Ocean 2A, and Ocean 3A, while another has U-571B, Ocean 1B, Ocean 2B, etc.)  They are used to introduce uncertainty as to the whereabouts of the submerged U-boats on the playing table.  Click HERE  for U-boat cards.  It is recommended to print the U-boat cards/Ocean cards on light blue card stock, though white card stock will work as well (Card stock is preferable to prevent the dark U-boat image from being visible from the reverse side.)  Each sheet of U-boats is laid out to provide two U-boat cards and six Ocean cards per sheet. 

Optional cards are provided HERE as playing aids showing the turn sequence on one side, and weapon ranges and hit probabilities on the other.

 Set Up:  While the Allied players turn their backs, the German players disperse their submerged U-boats (i.e. blank ocean side up) and Ocean cards anywhere in the designated Wolf Pack Area of a 5 x 7 table, preferably covered with a blue cloth.  Depending on the number of players, a larger surface may be necessary; 5 x 7 works well for approximately 10 players, five per side.  The Allies then form up their convoy in the rendezvous area and prepare to sail forward through the danger area enroute the opposite side of the table.   

Moving:  Destroyers have a range of 3 base lengths (or ‘3L’) per turn, Merchants 2L, and U-boats 1L while submerged, 3L on the surface (Diving and surfacing a U-boat does not count as movement, and may be done any time during a U-boat turn, though the U-boat is limited to one surfacing and one dive per turn.)  Ocean cards move 1L as well.  All units may move over or stop on top of any card with an ‘ocean side’ up, and any card ‘ocean up’ can move ‘through’ or ‘under’ any other card.  Note that if ‘stacked’ or overlapping ocean cards are later depth charged, the attack affects all the cards. 

Turns are limited to 90 degrees at a time, and can be made after each L of movement.  So a nimble destroyer could move ahead 1L, turn 90 degrees, move ahead another 1L, again turn 90 degrees, move ahead a final 1L, and then end with one last 90 degree turn.  A submerged U-boat, however, could only move 1L and then make a single 90 degree turn. 

 Searching with Sonar:  Destroyers may ‘ping’ one ‘ocean up’ card within 4L of their position at the beginning of their turn.  Roll 1d6.  On 4-6, briefly flip over the card. 

 Attacking with Torpedoes: Torpedoes have a range of 5L (1L = approx 4”).  To fire torpedoes, U-boats must rise to the surface at least briefly (flip card U-boat side up), fire up to 4 torpedoes, then can immediately submerge again (flip card ocean side up) or stay on the surface for a follow-on gun attack.  Up to two ships within range can be targeted regardless of U-boat orientation, although torpedoes need a clear path to the target.  To shoot between ships requires at least 1L separation.  Torpedoes may pass ‘through’ any ocean up card.  Roll 1d6 per torpedo; hits scored on 4-6.

 Attacking with Guns:  All ships and U-boats have at least one deck gun.  Guns can only engage one target at a time, and need a clear path to the target, though they can fire over the top of an ocean up card.  U-boats must surface to conduct a gun attack, and must end their turn on the surface.  To shoot between ships requires at least 1L separation. 

Merchant gun: range 3L; roll 1d6, hit on 5-6
U-boat gun: range 3L; roll 1d6, hit on 4-6
Destroyer guns: range 5L; roll 3d6, hits on 5-6

 Attacking with Depth Charges:  Destroyers may launch up to four depth charges per turn.  Depth charges may be launched on to ocean up cards or surfaced U-boat cards up to 1L away from either side or the stern in any pattern.  Roll 1d6 for each depth charge, hits on submerged targets 5-6, surface targets 3-6.  Note that if ocean/U-boat cards are overlapping, the depth charge attack affects ALL cards in contact with one another.  Tip: While U-boat players are expected to faithfully record depth charge damage to submerged U-boats, they DO NOT have to show whether or not a U-boat is actually under a particular ocean up card, even if a 5 or 6 is rolled.  The crafty player will pretend to mark damage even on an empty ocean card!

Ramming:  Any ship can ram surfaced U-boats.  To ram, the FRONT edge of the ship base must overlap the SIDE edge of a surfaced U-boat card.  Ramming does 1d6 worth of damage to the U-boat, most likely sinking it.  However, ramming will inflict 1 hit of damage to destroyers and TWO hits of damage to merchants, so ramming by merchants is a move of desperation!  Accidental collisions between ships results in the same damage. 

 Damage:  Hits of any kind reduce movement by 1L for each hit.  Last hit sinks the ship.  Destroyers have 4 hits points, U-boats 3, merchants 2.  Mark off collective damage on the card/base.  Note that U-Boats can dive and surface with one or more hits, but can no longer move laterally when submerged.  They must surface and remain on the surface if they take 2 hits.  If a U-boat is sunk while submerged, briefly turn the card over to show the U-boat (representing debris floating to the surface), and then turn face down again.  At this point, the card no longer moves.  However, if depth charged, the card should be played like an Ocean card and any hits fictitiously “marked off.”     

Turn Sequence

 1. Merchants move

2. Merchant gun attack

3. U-boats torpedo attack

4. U-boat gun attack

5. U-boats and Ocean cards move

6. Destroyers ping

7. Destroyers move/depth charge

8. Destroyers gun attack

 After the Merchants’ movement is complete, they may engage any surfaced U-boats within range with their gun.

 U-boats, which have been lying in wait and having anticipated the merchants’ movement, surface, fire torpedoes and conduct any gun attacks.  U-boats and Ocean cards now move, either first submerging (provided they did NOT conduct a gun attack this turn) and moving 1L, or remaining on the surface and moving up to 3L before diving at the end of their turn if they choose in order to confuse pursuing destroyers.

 After the German turn is complete, destroyers conduct sonar searches, and then move/attack.  Destroyers can drop depth charges while moving, though all depth charge attacks from different destroyers are resolved together.  For example, USS Rueben James and the HMS Reliant are conducting a coordinated depth charge attack (see figure).  Rueben James drops two depth charges on the ocean up card to his left side and one to his right.  He moves ahead 1L, and drops his fourth depth charge to his right.  On a parallel course ahead and to his right side is the Reliant, who drops one depth charge behind him on the same card with one charge dropped by Rueben James, moves ahead 2L and drops three charges to his left.  Once all movement and depth charging is complete the dice are rolled and the results noted.  Destroyers may now make any gun attacks.

 Winning:  The Allies win if they are able to get 50% of the merchant ships safely through the wolf pack and on to England; otherwise the victory goes to Germany and the U-boats.  A merchant is considered to have reach port once its front edge touches the far edge of the playing table or crosses a similar agreed upon line.