British Empire
Following the defeat of Japan in the Second World War, anti-Japanese resistance movements in Malaya turned their attention towards the British, who had moved to quickly retake control of the colony, valuing it as a source of rubber and tin. The fact that the guerrillas were primarily Malayan-Chinese Communists meant that the British attempt to quell the uprising was supported by the Muslim Malay majority, on the understanding that once the insurgency had been quelled, independence would be granted. The Malayan Emergency, as it was called, began in 1948 and lasted until 1960, but by 1957, Britain felt confident enough to grant independence to the Federation of Malaya within the Commonwealth. In 1963, the 11 states of the federation together with Singapore, Sarawak and North Borneo joined to form Malaysia, but in 1965 Chinese-majority Singapore was expelled from the union following tensions between the Malay and Chinese populations. Brunei, which had been a British protectorate since 1888, declined to join the union and maintained its status until independence in 1984.

Q: When did Singapore leave the Federation of Malaya?
1965