The Japanese invasion of the Philippines began with an invasion of Batan Island on December 8, 1941. When advancing Japanese forces threatened Manila, President Quezon, other senior officials of the Commonwealth government, and senior American military commanders relocated to Corregidor island, and Manila was declared an open city. On February 20, Quezon, his family, and senior officials of the Commonwealth government were evacuated from the island by submarine on the first leg of what came to be a relocation of the Commonwealth government in exile to the U.S.