The Battle of Plaman Mapu (27 April 1965) was one of the largest battles of the Indonesia-Malaysia Confrontation, a protracted undeclared war between Indonesia and a British-led Commonwealth of Nations over the creation of a new Malaysian state. The battle occurred as a result of an Indonesian effort to storm a British hilltop base at Plaman Mapu, on the border between the Malaysian state of Sarawak and Indonesia.