The following are my rules for Submarine Warfare (SW) and Convoy Disruption for the AA50 game:
Axis and Allies naval warfare rules model surface or fleet warfare quite well , but they do not represent submarine warfare (SW) well. A submarine's best defense is not its guns but the ability to hide and not be seen before or after an attack. SW is a series of battles between individual units or small groups of units. These rules are and attempt to model these two facets of SW.
These rules for SW apply only when all of the attacking or defending units in a sea zone are submarines. If there are any surface ships friendly to a submarine in the sea zone, then Fleet Rules (normal Axis and Allies rules) apply.
Submarines may enter and leave an enemy controlled sea zone without engaging in combat. The submarine owner chooses whether or not to engage in combat. A destroyer can end the movement of a submarine only if the destroyer can roll a spotting die roll of 3 or less as the sub attempts to leave the the destroyer’s sea zone. If successful, the destroyer cannot conduct any combat, it merely ends the movement of the submarine. Submarines that attack naval units do so using Fleet Rules (normal Axis and Allies rules).
If a submarine, that is not part of a surface fleet, is attacked, it must be attacked by SW rules. SW consists of a series of individual unit attacks and ends when all attacking units have completed their attacks or all defending units have been eliminated or the attacker breaks off the attack. Unescorted submarines may be attacked by aircraft and destroyers. Attacks can only occur after a spotting die roll has been made. Destroyers and aircraft can spot submarines on a roll of 3 or less.
Destroyers: If a destroyer spots a sub, then combat begins between that destroyer and sub. A destroyer hit on a 1 or 2, but on an attacking destroyer die roll of 6, the sub may escape and end the combat. Subs defend normally (hit on a 1).
**Aircraft:**When conducting a SW search, aircraft must expend 2 movement points to conduct a search in any sea zone. This means that fighters may conduct Anti-Submarine Warfare (ASW) only in sea zones adjacent to their base territory. Aircraft that roll a 3 or less, can make a surprise attack on a sub. Historically, aircraft would search the seas to try to find a submarine on the surface and quickly attack before the submarine could submerge. In game terms, aircraft can conduct one round of combat before the submarine can submerge and end the combat. During any round of combat, both the aircraft and the submarine may attack each other. a defending sub may choose to dive and end combat after any combat round is completed.
Combined Arms: An aircraft and a destroyer can work together to attack a submarine. an aircraft that makes its spotting die roll may choose to skip its attack and instead direct a destroyer to attack the sub, This way, the destroyer can use the aircraft as a spotter and the destroyer can do the combat.
Convoy Disruption occurs in the Collect Income phase as per Global40.2 rules with the following exceptions. Sea zones that are susceptible to convoy disruption (historical shipping lanes) are marked with “Convoy Disruption Limits”, a C1, C2, C3, etc. This represents the maximum number of IPCs that can be destroyed from that sea zone. Land territories are also marked with “Convoy Disruption Limits”, a C1, C2, C3, etc. this is the maximum IPC loss that can accrue to that territory. Convoy disruption is determined for each sea zone first. losses should be marked on the map with a die to record the damage. After all damage has been determined, the amount that accrues to each land territory is decided by the player inflicting the losses.
Convoy Disruption Limits for the AA50 map (partial list):
Sea Zones: Sz1:0 Sz2:C2 Sz3:C1 Sz4:C1 Sz5:C1 Sz6:C1 Sz7:C1 Sz8:C4 Sz9:C1 Sz10:C3 Sz11:0 Sz12:C1 Sz13:C1
The logic behind these numbers is that more highly travelled shipping lanes can have higher Convoy Disruption Limits than less travelled routes.
Territories: Archangel:C1 Norway:C1 England:C8 NWEurope:0 Germany:C1 France:C2 E.Canada:C1 E.US:C4 Morocco:0
The logic for assigning maximum land losses is that territories that are highly dependent on the import of raw materials and the export of finished products are highly susceptible, like England and Japan. Territories that transport most of their raw materials and finished goods by land are much less susceptible, like Germany and the US. Many small territories like Morocco and NW Europe have no susceptibility at all. Territories that are raw material producers , like Borneo and the East Indies, are susceptible 100% loss.
The Germans correctly deduced that England needed 60 million tons of imports annually to survive. This made England uniquely vulnerable to submarine warfare. A loss of the maximum amount possible to convoy disruption would mean not only economic collapse, but also starvation. No democracy can continue a war in the face of even small-scale starvation, so the following rule applies to England only. If England ever sustains the maximum amount of IPC loss (8 IPC) due to convoy Disruption, then England must sue for peace immediately. England, and the British empire, is out of the game. All English territories become neutral.
After Action Report (the results of one game of play testing):
As the German player, I purchased 2 subs per turn for the first 5 turns of a game. England destroyed about 2 subs per turn throughout the game. I never managed to get even 3 subs in position around England at any time during the game. A mathematical review of these rules show that Germany needs at least 4 subs in position around England to have even a small, 2% chance, of knocking England out of the war. They need 6 subs to have a reasonable, 30% chance, of knocking England out. Furthermore, German losses in submarine IPC value exceeded English IPC losses in units and Economic Disruption. My original rules had aircraft spotting on a die roll of 4 or less. This was changed to try to balance English and German losses.
The original rules said that SW attacks should be done in random order. This was time consuming and everybody hated it. Don’t try it. Attacker picks the attack order.
We forgot to do the 2 movement point expenditure for planes doing a search pattern every single time. We are just so used to fighters flying out 2 and back 2 spaces that we never did a search pattern expenditure. You decide if you like that rule.
The Big Question: Was it fun?
My best answer is “It depends”. I like variety in my games. I like technology, national advantages, event cards, and all other sources of variation in the game. I enjoyed this game because it was different. SW opens up an entirely new front in the war. England could no longer just sit back comfortably and just build up a larger and larger invasion force.
On the other hand, my opponent likes Axis and Allies as a chess game to be played over and over without variation in order to perfect his timing and strategy. He likes low luck and even extra low luck. He hated this houses rule. It spoiled his plans for Operation Overlord and changed all of his timing. SW rules and a maximum German effort to knock England out of the war would change the main focus of the war from the east front in Russia to the North Atlantic. That makes the game feel entirely different.
I would love to hear about other peoples' opinions and especially their experiences using these rules.