First he was half American, his mother was American. Maybe that's part of it. As to spilling American blood, well, Germany declared war on the US so Churchill didn't really get us into the fight in Europe. Although he certainly wanted us to. However, he was willing to spill just about everyone's blood senselessly: Australians at Singapore, Australians at Tobruk, and the Canadians at Dieppe. He truly believed in the British Empire and I suspect in the superiority of the British race or the English speaking peoples.