Port Moresby, also referred to as Pom City or simply Moresby, is the capital and largest city of Papua New Guinea. It is one of the largest cities in the southwestern Pacific outside of Australia and New Zealand. It is located on the shores of the Gulf of Papua, on the south-western coast of the Papuan Peninsula of the island of New Guinea. The city emerged as a trade centre in the second half of the 19th century. During World War II, it was a prime objective for conquest by the Imperial Japanese forces during 1942–43 as a staging point and air base to cut off Australia from Southeast Asia and the Americas.