Churchill's main accomplishment, in my humble opinion, was to keep British morale up and the British people willing to continue to sacrifice and endure while standing alone against Germany June 1940 to June 1941 and during the times of the great Soviet and British defeats in 1941 and 1942.

He was stubborn, a trait which is viewed as folly and idiocy if you are wrong and the the shining example in the darkness if you are right. He was a superb speaker and an excellent PR man, knowing how to grow his image and to sell the war to the citizens of the Empire.

He focused a bit too much on secondary or tertiary fronts and miscalculated the Japanese threat and mismanaged the Bengal famine 1943.

He did however, realise the absolute importance for victory that the Soviets remained in the fight, and the (highly needed at home) supplies, fighters and tanks he sent to the Soviets through dangerous routes (the Murmansk convoys suffered horrible casualties). I think it is a mark of a good leader that he can see past his own prejudiciers (Churchill was a staunch anti-communist) for the bigger picture. It was not until late 1943 that the US lend-lease to the Soviets exceeded the British one.

The British (and Canada) delivered 7 000 aircrafts, 5 000 tanks, 5 000 anti-tank guns, 15 million boots and 4 million tons of other war supplies to the Soviets.

If the British had not been in the war, would the Soviets have been able to withstand the German onslaught? Probably, but could they have taken the fight to Berlin? I doubt it. Would Germany have declared war on the US after Pearl Harbour without Britain in the fight? I doubt it again. And the US would have a very hard time to bring the fight to Europe without Britain to base off.