The pre-1941 timeline runs through Soviet actions in Poland, Finland, Romania, and the Baltic before Germany invaded the Soviet Union. Britain then adopted a pragmatic enemy's-enemy policy despite deep distrust of Stalin's regime. The Soviet Union kept German forces occupied on another front, which gave Britain a powerful reason to send aid. Its earlier cooperation with Hitler and attacks on neighbouring states made the alliance uneasy from the outset.
Notable Point · 2:01-6:44
Soviet diplomacy and the politics behind the convoys
A wartime timeline explains why aid to the Soviet Union was a strategic choice for Britain, not a simple partnership of shared aims.