Japanese invasion of Malaya in the context of "Malayan Peoples' Anti-Japanese Army"

The attack on Pearl Harbor was a surprise military strike by the Empire of Japan on the United States Pacific Fleet at its naval base at Pearl Harbor on Oahu, Hawaii, on December 7, 1941. At the time, the U.S. was a neutral country in World War II. The air raid on Pearl Harbor, which was launched from aircraft carriers, resulted in the U.S. declaring war on Japan the next day. The Japanese military leadership referred to the attack as the Hawaii Operation and Operation AI, and as Operation Z during its planning.

The attack on Pearl Harbor was preceded by months of negotiations between the U.S. and Japan over the future of the Pacific. Japanese demands included that the U.S. end its sanctions against Japan, cease aiding China in the Second Sino-Japanese War, and allow Japan to access the resources of the Dutch East Indies. Japan sent out its naval attack group on November 26, 1941, just prior to receiving the Hull note, which stated the U.S. desire that Japan withdraw from China and French Indochina. Isoroku Yamamoto, commander of the Japanese Combined Fleet, planned the attack as a pre-emptive strike on the Pacific Fleet, based at Pearl Harbor since 1940 in order to prevent it from interfering with Japan's planned actions in Southeast Asia. Yamamoto hoped that the strike would enable Japan to make quick territorial gains and negotiate peace. In addition to Pearl Harbor, over seven hours Japan launched coordinated attacks on the U.S.-held Philippines, Guam, and Wake Island; and on the British Empire in Malaya, Singapore, and Hong Kong.

The Unfederated Malay States (Malay: Negeri-Negeri Melayu Tidak Bersekutu; Jawi: نݢري٢ ملايو تيدق برسکوتو) was the collective term for five distinct British protected states situated in the Malay Peninsula during the early to mid-twentieth century. These states were Johor, Kedah, Kelantan, Perlis and Terengganu. In contrast to the neighbouring Federated Malay States comprising Selangor, Perak, Pahang and Negeri Sembilan, the Unfederated Malay States did not share a unified administration or common institutions. Though they were nominally independent, each of them functioned as an individual protectorate under British oversight and were not recognised as a single entity in international law.

Following the conclusion of World War II, the British crown colony known as the Straits Settlements was formally de jure dissolved in 1946 (having been rendered de facto defunct with the Japanese occupation of Malaya and the Fall of Singapore in 1942). Penang and Malacca were subsequently combined with both the Unfederated and Federated Malay States to form the Malayan Union. Singapore was administratively separated and established as a standalone crown colony directly governed by the United Kingdom, independent of any Malayan political framework.