bersiap is the name given by the dutch to a violent and chaotic phase of the indonesian national revolution following the end of world war ii. the indonesian word bersiap means 'get ready' or 'be prepared'. the bersiap period lasted from august 1945 to december 1946.
the period started with revolutionary violence occurring during the increasing power vacuum left by the retreating japanese occupational forces and the gradual buildup of a british military presence but before the official handover to a dutch military presence. the term refers to that period when, after being kidnapped by republican youths (pemuda), sukarno declared independence on 17 august 1945.
the period ended with the departure of the british military in 1946, by which time the dutch had rebuilt their military capacity. meanwhile, the indonesian revolutionary fighters were well into the process of forming a formal military. the last japanese troops had been evacuated by july 1946.