Early in the Second World War, RAN ships again operated as part of Royal Navy formations, many serving with distinction in the Mediterranean, the Red Sea, the Persian Gulf, the Indian Ocean, and off the West African coast. Following the outbreak of the Pacific War and the virtual destruction of Allied naval forces in south-east Asia, the RAN operated more independently, defending against Axis naval activity in Australian waters, or participating in United States Navy offensives. As the navy took on an even greater role, it was expanded significantly and at its height the RAN was the fourth-largest navy in the world, with 39,650 personnel operating 337 warships. A total of 34 vessels were lost during the war, including three cruisers and four destroyers.