Osmena was Vice-President of the Philippines under QUEZON and accompanied him to the USA after the Philippines fell. There he took over many Presidential duties because of Quezon’s ill health. Osmena sat on the Pacific War Council and attended many other conferences and board meetings which discussed military and other matters of concern to the Philippines. He also lectured throughout the USA on the Philippine situation. When Quezon died in August 1944 Osmena became President.
Because of his intense dislike of MACARTHUR, it took much persuasion to get Osmena to accompany the Luzon invasion of January 1945. However, he did return and with Romulo and MacArthur helped to integrate the Filipino guerrilla forces with the US Army. Osmena became head of the new civilian government after the liberation.