When British Prime Minister Winston Churchill heard that Japan had bombed Pearl Harbor, he immediately called American President Franklin D Roosevelt. Roosevelt told him "They have attacked us at Pearl Harbor. We are all in the same boat now."
Churchill later wrote:
"No American will think it wrong of me if I proclaim that to have the United States at our side was to me the greatest joy. I could not foretell the course of events. I do not pretend to have measured accurately the martial might of Japan, but now at this very moment I knew the United States was in the war, up to the neck and in to the death. So we had won after all!
"Yes, after Dunkirk; after the fall of France; after the horrible episode of Oran; after the threat of invasion, when, apart from the Air and the Navy, we were an almost unarmed people; after the deadly struggle of the U-boat war - the first Battle of the Atlantic, gained by a hand's-breath; after seventeen months of lonely fighting and nineteen months of my responsibility in dire stress. We had won the war. England would live; Britain would live; the Commonwealth of Nations and the Empire would live.
"How long the war would last or in what fashion it would end no man could tell, nor did I at this moment care. Once again in our long Island history we should emerge, however mauled or mutilated, safe and victorious.
"We should not be wiped out.
"Our history would not come to an end. We might not even have to die as individuals.
"Hitler's fate was sealed. Mussolini's fate was sealed. As for the Japanese, they would be ground to powder."