The Second World War o The aircraft of his command were destroyed; the naval forces were ordered to leave; and because of the circumstances in the Pacific region, reinforcement and resupply of his ground forces were impossible. Under the pressure of superior numbers, the defending forces withdrew to the Bataan Peninsula and to the island of Corregidor at the entrance to Manila Bay. o Manila, declared an open city to prevent its destruction, was occupied by the Japanese on January 2, 1942.