America jumped in to help."

Troll, I've made this point several times on this forum: America did not "jump in to help." America prevaricated. Even after Pearl Harbor, and to FDR's frustration, America prevaricated. Fortunately for the UK and Russia, Hitler resolved the matter for us, by declaring war on America.

Does anyone know if USSR/Russia has any significant date for remembrance? It could be that every date in the calendar is worth remembering for them: the scale of their losses was almost beyond comprehension. (More Russians died at Stalingrad than on both sides in the whole of WW1.)

But obviously it's not only about scale. There were presumably far heavier American losses later in the war (in the advance on Japan), and in circumstances where the combatants knew better the horrors they were getting into, than at Pearl Harbor?