Why did the Soviet Union enter the war early in February 1941?

[mamahuhu]

I am playing a head-to-head game with a friend. He controls the Axis powers, and I play as the Allies.

From the start up to January 1941, the general course of events followed history. Germany and the Soviet Union partitioned Poland, and the Soviet Union attacked Finland. Germany launched its offensive in the Western Front in the spring of 1940, and France surrendered in September 1940. Hungary, Romania and other nations joined the Axis bloc. In Asia, Japan kept pressing its attacks against China, and Communist Chinese forces entered the war at the end of 1940.

Here are the deviations from historical events or conventional gameplay: Germany recognized the Vichy French regime, but declared war on and eliminated Vichy France in the subsequent turn. Germany annexed Lithuania and did not leave it for the Soviet Union; as a result, the Soviet Union only occupied the remaining Estonia and Latvia. The Italian Navy escaped the Mediterranean from Gibraltar. Instead of heading for the English Channel, it sailed south, yet it was completely annihilated by the Royal Navy in the Indian Ocean by the end of 1940. Per our house rules, Germany declared war on Yugoslavia in January 1941 and easily occupied it in the following turn.

Then the strange incident occurred: At the end of the Allied turn on January 31, 1941, we received the message "The Soviet Union is preparing for war", and Soviet war readiness reached 92%. When the Axis turn for February 1941 ended, the Soviet Union entered the war and joined the Allied side. All Soviet units along the Soviet-German border were automatically deployed. However, under this condition, the Soviet Union had not declared war on Germany; the two sides remained in a standoff with no active combat.

At first, we assumed that either too many or too few Axis troops stationed along the Soviet-German border triggered the sharp rise in Soviet war readiness. After testing, however, the number of his Axis units on the Soviet-German border was neither below 4 nor above 18, so this should not have triggered the event that accelerates Soviet war preparation.

So what could cause the Soviet Union to suddenly enter the war as early as February 1941?

[firsteds]

Here is a list of some of the things that can increase USSR mobilisation beyond normal:

1. Germany taking Poland in one turn
2. USSR not invading Finland
3. Germany annexing Lithuania (BIG)
4. Every single AXIS DoW (e.g. Belgium, Lux, Denmark). The increase is only small but they all add up, The only exception is Greece if the DoW is by the Italian event.
5. Insufficient units in Manchuria
6. The surrender of Yugoslavia (not just the DoW)
7. Axis units close to Cairo
8. Too few units in Poland up to 1941
9. Too many units in Poland after 1941
10. Too many units in Romania after 1941
11. Sea Lion

As you can see, a lot can go wrong. Manchuria is often the issue but you would have seen a warning. There are messages if you trigger Manchuria, Cairo or Sea Lion. There is a pre warning for Lithuania. There are no messages for the other triggers apart from the map borders re Poland and Romania.

That's all I can think of just now. Let me know if you need further details.

[mamahuhu]

Thanks for your input.
I checked with my opponent again. His garrisons in Northeast China are kept at the required level and have not been reduced.

In this game, Germany took 2 turns to defeat Poland.
Italy not only did not declare war on Greece, but voluntarily abandoned North Africa.
I proceeded with my attack on Finland as per the usual play.
He also did not launch Operation Sealion.

That means reasons 1, 2, 4, 5, 7 and 11 are not applicable here.

It is true that Germany annexed Lithuania, which provokes the Soviet Union. However, in our previous game, his Germany annexed Lithuania as well, yet the Soviet Union did not enter the war this early in that match.

So my leading hypothesis now is that this may come down to the number of troops deployed along the border. Still, we did not expect this factor alone to be enough to trigger such an early Soviet entry into the war.

[BillRunacre]

If there were insufficient Japanese units in Manchuria, or too few/many Axis units along the Soviet border, then there would have been messages every turn this was the case, pointing this out.

If you press L on your keyboard you can see a list of all messages that will have appeared during the game so far, and much more, so if you haven't done so already I suggest checking this area.

[firsteds]

If there were insufficient Japanese units in Manchuria, or too few/many Axis units along the Soviet border, then there would have been messages every turn this was the case, pointing this out.

Is this correct for "too few/many units on the soviet border?" I thought it was only true for Manchuria. For the soviet border the map markers change (e.g. they turn red and relocate and the mouse over text changes) but I don't think there are warning messages every turn (or any turn). Nor any messages that can be seen in the Log. I always thought it was up to the Axis player to count the units, look at the map markers and monitor USSR mobilisation. I can't recall seeing a pop up message or a log entry. I will try and test it in a game. Apologies if I have this wrong.

[Umeu]

would actually also be nice if the zone in Poland would be visible when you did not reach the threshold of too many units. I've had plenty of games where I misjudged the zone by 1 hex, and threw a wrench in my best-laid plans... It's quite tedious to always do the counting.

[BillRunacre]

would actually also be nice if the zone in Poland would be visible when you did not reach the threshold of too many units. I've had plenty of games where I misjudged the zone by 1 hex, and threw a wrench in my best-laid plans... It's quite tedious to always do the counting.

There are markers to show both 6 and 10 hexes from Warsaw, with labels explaining each one, so you may have to count units, but you certainly won't have to count hexes.

[taffjones]

Hi Bill.
I see markers for the 6 hexes from Warsaw but not markers for 10 hexes. It's a feature I asked for years ago but have never seen and I am updated to the latest version.
All other markers show up.
Is there anything I am missing to be able to see them?

[LoneRunner]

Hi Bill.
I see markers for the 6 hexes from Warsaw but not markers for 10 hexes. It's a feature I asked for years ago but have never seen and I am updated to the latest version.
All other markers show up.
Is there anything I am missing to be able to see them?

I see markers for 10 hexes in my current online game. I believe the markers did not show up until 1941. Maybe that's why you don't see them?