World War II: Philippine Commonwealth troops under the Philippine Commonwealth Army units enter the province of Ilocos Sur in Northern Luzon and attack Japanese Imperial forces.
The Imperial Japanese Army was the official ground-based armed force of the Empire of Japan from 1868 to 1945. It was controlled by the Imperial Japanese Army General Staff Office and the Ministry of the Army, both of which were nominally subordinate to the Emperor of Japan as supreme commander of the army and the Imperial Japanese Navy. Later an Inspectorate General of Aviation became the third agency with oversight of the army. During wartime or national emergencies, the nominal command functions of the emperor would be centralized in an Imperial General Headquarters (IGHQ), an ad hoc body consisting of the chief and vice chief of the Army General Staff, the Minister of the Army, the chief and vice chief of the Naval General Staff, the Inspector General of Aviation, and the Inspector General of Military Training.
The Commonwealth of the Philippines (Spanish: Commonwealth de Filipinas or Mancomunidad de Filipinas; Tagalog: Kómonwélt ng Pilipinas or Malasariling Pámahalaán ng Pilipinas) was the administrative body that governed the Philippines from 1935 to 1946, aside from a period of exile in the Second World War from 1942 to 1945 when Japan occupied the country. It was established following the Tydings–McDuffie Act to replace the Insular Government, a United States territorial government. The Commonwealth was designed as a transitional administration in preparation for the country's full achievement of independence. Its foreign affairs remained managed by the United States.During its more than a decade of existence, the Commonwealth had a strong executive and a Supreme Court. Its legislature, dominated by the Nacionalista Party, was at first unicameral, but later bicameral. In 1937, the government selected Tagalog – the language of Manila and its surrounding provinces – as the basis of the national language, although it would be many years before its usage became general. Women's suffrage was adopted and the economy recovered to its pre-Depression level before the Japanese occupation in 1942.
In 1946, the Commonwealth ended and the Philippines claimed full sovereignty as provided for in Article XVIII of the 1935 Constitution.