But Russia did determine her own destiny. She had already beaten the Germans during Op Typhoon, the last push on Moscow. The first Lend-Lease shipments of any value to the Russians did not arrive until well into '42, after the danger of Russia immediately folding had passed.
Lend-lease helped the USSR to win the war faster, and with less casualties. Without Lend-lease they most likely still would have been on the winning side.

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It's a sick, sick world. I'm a happy man.