A boycott against foreign goods particularly hurt Britain, which was well established in China. The campaign soon spread to Hong Kong, where strikes in the 1920s caused agitation. When the Sino-Japanese War broke out in 1937, Hong Kong was once more a refuge, with thousands of Chinese fleeing to it before the advancing Japanese. With the outbreak of warin Europe in 1939, the position of the colony became more precarious, as it was now a target; the Japanese attacked and occupied Hong Kong in December 1941. During the war years Hong Kong’s commerce was drastically impaired; food was scarce, and many residents fled to inland China. The population, which had numbered 1,600,000 in 1941, was reduced to about 650,000 by 1945 when the Japanese surrendered. Britannica