On 17 August 1945, just two days after Japan had admitted defeat in World War Two, Indonesia proclaimed its independence from Dutch colonial rule. The man doing the proclaiming was the new nation’s first leader, President Sukarno. See https://www.youtube.com/watch?v=ZRU93–5aOg
It wasn’t smooth sailing. The Netherlands did not accept the proclamation but was unready to reinstall government there immediately, so – ironically – the Japanese were left with the task of keeping the peace until Allied command for Southeast Asia (SEAC) could sent troops in. Indonesian nationalists didn’t fancy any of the above and hostilities broke out. In some cases, sympathetic Japanese commanders allowed arms and munitions to fall into the hands of the nationalists.
Then SEAC sent in its troops, mainly Indian sepoys with British brass. Hell broke loose. You can read about it at these links: DUTCH EAST INDIES October 1945: the Battle of Surabaya part 1 and DUTCH EAST INDIES November 1945: the Battle of Surabaya part 2.
After five years of struggle, Indonesia was finally recognised as an independedent nation. Happy Birthday, Indonesia!