@ 1948 - Independence

The demand for country independence arose subsequent to the independence of India after WWI. Sri Lanka was only involved in the WWI as a part of the British Empire. However, Allies' wartime propaganda about the virtue of freedom and self-determination of nations, heard and noted by Sri Lanka nationalist, had sparked off the growth of nationalism in Sri Lanka. In 1915, the British misconstrued the communal riot and uprising that broke out in the west coast as antigovernment conspiracy and consequently put it down with brutal forces. This was considered the turning point in the nationalist movement in Sri Lanka.

Learning that, in 1917, the Indian National Congress and the Muslim League in India had joined for more nationalist progression, two years later, in 1919, the major Sinhalese and Tamil political organization in Sri Lanka united to form the Ceylon National Congress which proposed for a new constitution which was then written in 1920. The constitution was amended in 1924 which resulted in increasing Sri Lankan representations. However, as the changed constitution failed to provide qualified representative persons for government, in 1931, further constitutional changes were implemented providing Sri Lankan a practice of self-government and allowing Sinhalese and Tamils to further extend their influence in government.

During WWII, Sri Lanka became a central base for British operations in Southeast Asia after felling of Singapore to the Japanese in February 1942. In this time, Sri Lanka was not only the base for warfare operations but it was also the supplier for essential products for Allies especially rubber enabling the country to save a surplus in a hard currency. As its role of a seat of the Southeast Asia command, a broad infrastructure of health services and modern amenities was built to accommodate the large number of troops posted into all parts of the country. The inherited infrastructure improved the standard of living in the postwar.

Relationships between British and Sri Lanka that were maintained since WWII influenced British to eventually promise the full participatory government after the war. British negotiated the island's dominion status with the Vice Chairman of the Board of Ministers, Don Stephen Senanayake, who also the founder and the leader of the United Nation Party (UNP). The negotiation ended with the Ceylon Independence Act of 1947 which formalized the transfer of power which was later implemented as a new constitution (and making Sri Lanka a dominion) on 4th February 1948.