In the First World War, Devonport was the headquarters of Western Approaches Command until 1941 and Sunderland flying boats were operated by the Royal Australian Air Force. It was an important embarkation point for US troops for D-Day. The city was heavily bombed by the Luftwaffe, in a series of 59 raids known as the Plymouth Blitz. Although the dockyards were the principal targets, much of the city centre and over 3,700 houses were completely destroyed and more than 1,000 civilians lost their lives. This was largely due to Plymouth's status as a major port Charles Church was hit by incendiary bombs and partially destroyed in 1941 during the Blitz, but has not been demolished, as it is now an official permanent monument to the bombing of Plymouth during World War II.