With the outbreak of World War II, the Americans designated the building as a bomb shelter and evacuation center. When the invading Japanese forces arrived in Manila, they used the abandoned building as headquarters for senior officers. During the Battle of Manila in 1945, the Japanese used it as a garrison and command post, before being burned, sustaining substantial damage to the roof and ballroom. After the combined Filipino and American forces recaptured the city, the US Army and Navy Engineering Corps rebuilt the building and it opened again on 1 December 1945.