When was Britain allied to Nazi Germany? Genuinely puzzled by that one. Do you mean Chamberlain? He signed a treaty, not an alliance, over Czechovaklia that Hitler immediately broke. He didn't invade the other half of Czechovaklia at the same time as the Nazis, as Stalin did in 1939 over Poland, then spend 2 years giving the Germans raw materials and fuel for their war machine.
Nazi Military Alliances: Italy Japan Hungary Romania Slovaks Bulgaria Croatia Yugoslavia Spain Finland China Denmark
Neither Russia nor Britain had a military alliance with the Nazis Both had agreements with Nazis promising not to fight each other and to let the Nazis take other people's land "Munich Agreement" of 1938 and "Molotov-Ribbentrop Pact" of 1939
The Soviet agreement with the Nazis included a secret plan for the Soviets to militarily invade the Eastern half of Poland after the Germans had militarily invaded the Western half. That's a military pact. The Munich agreement (that the Germans promptly broke anyway) included no such military cooperation. It's like comparing apples and pears.
Utterly shameful, no denying, but Britain didn't militarily invade one half of Czechovaklia whilst the Germans militarily invaded the other - that's the definition of a military pact, and I'm sticking to that. Britain was involved in a failed treaty with Nazi Germany, something it undertook in a half-arsed attempt to stem the development of Nazi hegemony over mainland Europe, not to militarily enhance its own imperialist agenda: that is what the Soviet Union did, pure and simple.
