Definitely “not purely”. The British bombed the Germans for at least two years before the US came into the fight, not to mention the Russians who tore the guts out of the German army. The British were running agents in Europe against the Nazis for a long time before we got there. Also, the Dutch, Norwegians, French and Belgians all contributed to the struggle.
Bur let me be clear about one thing: the Russians and the British and our other allies could not have completed their tasks without the massive - and I do mean massive - American food, fuel, equipment and the other arms supplies needed to subdue Germany. Russia was clearly “on the ropes”, until Great Britain and Uncle Sugar came along and gave them the equipment needed to finish the job.
I give great and immense credit to the British for not throwing in the towel when common sense might have told them otherwise. Without Britain, I don’t frankly know how we could have invaded Europe with our allies. And it wasn’t just us: the Canadians were in the Normandy landings with the US, and Britain. It was a team effort from the git-go. Heck, I give great credit to the Russians for not folding and holding out because it was in Russia that the German army met its gotterdammerung. Invading Russia was Hirler’s undoing because it was a tar baby Germany could not conquer but could not disengage from either.They literally prepared and signed their own death warrants when they invaded Russia.
I’m struck, though, by the fact that the Russians suffered titanic defeats at the start of the war but did not surrender. One disaster after another and yet they hung in there. In the end, they inflicted massive casualties on the Germans and bled them white, but what I find illuminating is that the Russians absorbed all those body blows . When the tables finally turned, it took only a couple of massive German defeats to put them on the back foot.
The common denominator here is aid from the new world (including of course Canada) saved the Russians’ and British’s bacon. I note also that Great Britain sent as much aid as it could to the Russians. And let’s try to not forget that at the same time, the US, Australians and Dutch Were in a death struggle with Japanese Imperial Navy and Army over a gigantic ocean area.
It was a team effort.