Final answer:
Winston Churchill was reappointed as First Lord of the Admiralty, overseeing the Royal Navy, not a specific fleet. Britain and the U.S. focused on a Europe First strategy due to the immediate threats from Germany, while the U.S. had the most to lose in the Pacific due to its territories and interests there.
Step-by-step explanation:
Winston Churchill was reappointed as First Lord of the Admiralty, which is the political head of the Royal Navy, at the outset of the Second World War in 1939. This position is not to be confused with specific fleet commands such as the Atlantic, Pacific, or Mediterranean fleets. It is a broader role overseeing the entirety of the Royal Navy, which was essential to Britain's war effort against the Axis powers.
Churchill's preferences for a 'Europe First strategy' were largely influenced by Britain's geopolitical position and immediate security threats. As the United Kingdom faced the possibility of invasion and sustained attacks by Germany, prioritizing the European theatre was essential. The United States, under President Roosevelt, agreed upon a similar strategy with the Atlantic Charter and through military planning, which emphasized defeating Germany and Italy before turning full attention to Japan in the Pacific. Moreover, the Allied nation with the most to lose in the Pacific was the United States, as evidenced by the attack on Pearl Harbor and the fact that the U.S. had significant territories and interests in the Pacific region.
Admiral Chester Nimitz was the commander of the U.S. Pacific Fleet during World War II and played a pivotal role in the conflicts there, contrasting the strategic focus in Europe.