In real history, Hitler attack on 22. June 1941 Soviet Union. But what if Soviets are better intelligence information and they know more of Germans plans and attack first?
PS : Forgive me my bad English, this isnt' my first language.
Hammerstrike : Part 1
18. December 1940 : Hitler gives order to preparing attack against Soviet Union with code name "Barbarossa", planned attack day is 15. May 1941.
29. December 1940 : Soviets get know Hitler plans, they start investigation to get more info about attack.
16. January 1941 : Soviets starts a mobilization and preparings for war, Stalin wants attack first.
19. January 1941 : Soviets get know attack day, Stalin puts attack day in 1. May and warns Tuva and Mongolia against possible Japanese attack.
30. January 1941 : Germans get know Soviet war preparations, Hitler moves attack day earlier, in 1. May.
31. January 1941 : Germans warns all Anti-Comitern pact countries, Portugal and Turkey against Soviet attack, but only Finland, Slovakia, Hungary, Romania and Italy with her puppet Albania believe that information.
1. February 1941 : Germans, who want form maximum plausible coalition against Soviets, warns Yugoslavia.
4. February 1941 : Rippentrop meets Yugoslavian regent Prince Paul, Yugoslavia promises join Axis.
25. February 1941 : Yugoslavia joins officially Axis.
27. February 1941 : Pro-Allies coup in Yugoslavia, new government leaves Axis. Hitler is furious and plans attack Yugoslavia before USSR, but moves Barbarossa starting day in 1. April too, because he scares Soviet attack.
9. March 1941 : Germany, Hungary and Italy with Albania attacks Yugoslavia, Operation nr 25 begins. Germany gives a ultimatum for Greece : They order Allies units leave in 23. March, makes peace with Italy and Albania in pre-war borders and joins coalition against USSR, or Germany declared war on them.
10. March 1941. Bulgaria attack Yugoslavia. Greece refuses an ultimatum.
11. March 1941. Germany and Bulgaria declares war on Greece, operation Marita begins.
12. March 1941 : Hitler understand, that first he need ended wars in Balkan and moves Barbarossa starting day back in 20. April.
13. March 1941 : Croatia is formed, German and Bulgarian units take Saloniki in Greece.
15. March 1941: Yugoslavian capital Belgrade is taken by germans.
16. March 1941 : Romania declares war on Yugoslavia. Stalin moves attack day in 15. April.
20. March 1941 : Yugoslavia captures, italian puppet state Montenegro is founded. Stalin moves attack day in 10. April.
25. March 1941 : Yugoslavia is dissolved, lands is partioned between Germany, Italy, Albania, Hungary, Bulgaria, Croatia, Montenegro and German puppet state Serbia like OTL.
29. March 1941 : Athens is taken by German forces, Hitler is very happy and he believes even more for earlier, that German army is unstoppeble and give order to attack Soviets in 5. April.
30. March 1941 : Greece captures. Soviets get know Hitler plans, Stalin give order attack in 3. April.
31. March 1941 : Greece is partioned between Italian, Bulgarian and German occupation zones and Bulgaria like OTL, but Hitler dont give a order to attack Crete, because he needs ool units in war with USSR.
1. April 1941 : Pro-German coup in Iraq.
3. April 1941 : 05.45 AT MORNING, SOVIET UNION DECLARES WAR ON GERMANY, FINLAND, HUNGARY AND SLOVAKIA AND ATTACK THEM. THEY DONT ATTACK ROMANIA, BECAUSE UNITS ARNT' READY AND THEY HOPE THAT ROMANIA DONT RISK ATTACK FIRST. OPERATION HAMMERSTRIKE IS BEGIN!
PS : Forgive me my bad English, this isnt' my first language.
Hammerstrike : Part 1
18. December 1940 : Hitler gives order to preparing attack against Soviet Union with code name "Barbarossa", planned attack day is 15. May 1941.
29. December 1940 : Soviets get know Hitler plans, they start investigation to get more info about attack.
16. January 1941 : Soviets starts a mobilization and preparings for war, Stalin wants attack first.
19. January 1941 : Soviets get know attack day, Stalin puts attack day in 1. May and warns Tuva and Mongolia against possible Japanese attack.
30. January 1941 : Germans get know Soviet war preparations, Hitler moves attack day earlier, in 1. May.
31. January 1941 : Germans warns all Anti-Comitern pact countries, Portugal and Turkey against Soviet attack, but only Finland, Slovakia, Hungary, Romania and Italy with her puppet Albania believe that information.
1. February 1941 : Germans, who want form maximum plausible coalition against Soviets, warns Yugoslavia.
4. February 1941 : Rippentrop meets Yugoslavian regent Prince Paul, Yugoslavia promises join Axis.
25. February 1941 : Yugoslavia joins officially Axis.
27. February 1941 : Pro-Allies coup in Yugoslavia, new government leaves Axis. Hitler is furious and plans attack Yugoslavia before USSR, but moves Barbarossa starting day in 1. April too, because he scares Soviet attack.
9. March 1941 : Germany, Hungary and Italy with Albania attacks Yugoslavia, Operation nr 25 begins. Germany gives a ultimatum for Greece : They order Allies units leave in 23. March, makes peace with Italy and Albania in pre-war borders and joins coalition against USSR, or Germany declared war on them.
10. March 1941. Bulgaria attack Yugoslavia. Greece refuses an ultimatum.
11. March 1941. Germany and Bulgaria declares war on Greece, operation Marita begins.
12. March 1941 : Hitler understand, that first he need ended wars in Balkan and moves Barbarossa starting day back in 20. April.
13. March 1941 : Croatia is formed, German and Bulgarian units take Saloniki in Greece.
15. March 1941: Yugoslavian capital Belgrade is taken by germans.
16. March 1941 : Romania declares war on Yugoslavia. Stalin moves attack day in 15. April.
20. March 1941 : Yugoslavia captures, italian puppet state Montenegro is founded. Stalin moves attack day in 10. April.
25. March 1941 : Yugoslavia is dissolved, lands is partioned between Germany, Italy, Albania, Hungary, Bulgaria, Croatia, Montenegro and German puppet state Serbia like OTL.
29. March 1941 : Athens is taken by German forces, Hitler is very happy and he believes even more for earlier, that German army is unstoppeble and give order to attack Soviets in 5. April.
30. March 1941 : Greece captures. Soviets get know Hitler plans, Stalin give order attack in 3. April.
31. March 1941 : Greece is partioned between Italian, Bulgarian and German occupation zones and Bulgaria like OTL, but Hitler dont give a order to attack Crete, because he needs ool units in war with USSR.
1. April 1941 : Pro-German coup in Iraq.
3. April 1941 : 05.45 AT MORNING, SOVIET UNION DECLARES WAR ON GERMANY, FINLAND, HUNGARY AND SLOVAKIA AND ATTACK THEM. THEY DONT ATTACK ROMANIA, BECAUSE UNITS ARNT' READY AND THEY HOPE THAT ROMANIA DONT RISK ATTACK FIRST. OPERATION HAMMERSTRIKE IS BEGIN!