The United Kingdom took part in World War II from 3 September 1939 until 15 August 1945. At the beginning of the war in 1939, London was the largest city in the world, with 8.2 million inhabitants. It was the capital not just for the United Kingdom, but for the entire British Empire. London was central to the British war effort. It was the favourite target of the Luftwaffe (German Air Force) in 1940, and in 1944-45 the target of the V-1 cruise missile, the V-2 rocket, and the unsuccessful V-3 "London gun".
An estimated 18,688 civilians in London were killed during the war, 0.23% of the population. 1.5 million were made homeless. 3.5 million homes and 9,000,000 square feet (840,000 m2) of office space were destroyed or damaged.