The Battle of Hong Kong (8–25 December 1941), also known as the Defence of Hong Kong and the Fall of Hong Kong, was one of the first battles of the Pacific War in World War II. On the same morning as the attack on Pearl Harbor, forces of the Empire of Japan attacked the British Crown colony of Hong Kong, without declaring war against the British Empire. The Hong Kong garrison consisted of British, Indian and Canadian units, also the Auxiliary Defence Units and Hong Kong Volunteer Defence Corps (HKVDC). Within a week the defenders abandoned the 2 of the 3 territories of Hong Kong (Kowloon and New Territories) on the mainland, and less than two weeks later, with their last territory Hong Kong Island untenable, the colony surrendered. Background Britain first thought of Japan as a threat with the ending of the Anglo-Japanese Alliance in 1921, a threat that increased throughout the 1930s with the escalation of the Second Sino-Japanese War. On 21 October 1938 the Japanese occupied Canton (Guangzhou) and Hong Kong was surrounded. British defence studies concluded that Hong Kong would be extremely hard to defend in the event of a Japanese attack, but in the mid-1930s work began on improvements to defences including along the Gin Drinkers' Line. By 1940, the British determined to reduce the Hong Kong Garrison to only a symbolic size. Air Chief Marshal Sir Robert Brooke-Popham, the Commander-in-Chief of the British Far East Command argued that limited reinforcements could allow the garrison to delay a Japanese attack, gaining time elsewhere. Winston Churchill and the general staff named Hong Kong as an outpost, and decided against sending more troops. In September 1941, they reversed their decision and argued that additional reinforcements would provide a military deterrent against the Japanese and reassure Chinese leader Chiang Kai-shek that Britain was serious about defending the colony. The plan for the defence of Hong Kong was that a delaying action would be fought in the New Territories and Kowloon peninsula to allow the destruction of vital infrastructure and stores there. The Gin Drinker's Line was expected to hold out for at least three weeks, following which all defenders would withdraw to Hong Kong Island which would be defended and use of the harbour denied until reinforcements could arrive from Singapore or the Philippines. According to the history manual of the United States Military Academy: "Japanese control of