The Battle of Guam was an engagement during the Pacific War in World War II, and took place from 8 December to 10 December 1941 on Guam in the Mariana Islands between Japan and the United States. The American garrison was defeated by Japanese forces on 10 December, which resulted in an occupation until the Second Battle of Guam in 1944.

The Pacific War, sometimes called the Asia–Pacific War or the Pacific Theater, was the theater of World War II that was fought in eastern Asia, the Pacific Ocean, the Indian Ocean, and Oceania. It was geographically the largest theater of the war, including the vast Pacific Ocean theater, the South West Pacific theater, the Second Sino-Japanese War, and the Soviet–Japanese War.