 The Indonesian 'encirclement and annihilation' campaign of 1977–1978 broke the back of the main Fretilin militia and the capable Timorese President and military commander, Nicolau Lobato, was shot and killed by helicopter-borne Indonesian troops on 31 December 1978.The 1975–1978 period, from the beginning of the invasion to the largely successful conclusion of the encirclement and annihilation campaign, proved to be the toughest period of the entire conflict, costing the Indonesians more than 1,000 fatalities out of the total of 2,000 who died during the entire occupation.The Fretilin militia who survived the Indonesian offensive of the late 1970s chose Xanana Gusmão as their leader.