By mid-December 1963, Indonesian had sent a commando unit consisting of 128 volunteers and 35 regular soldiers to Sebatik. Their aim was to take Kalabakan, then invade Tawau and Sandakan. On 29 December 1963, the Indonesian unit attacked the 3rd Royal Malay Regiment unit. The Indonesians managed to throw several grenades into the totally unprepared Malay Regiment's sleeping quarters. The attack resulted in eight Malay soldiers being killed and nineteen wounded. Malaysian armed police eventually drove the attackers north after a two-hour battle.