of Borneo between 1 and 10 May. The PT boats carried Netherlands Indies Civil Administration interpreters on most patrols who interrogated natives to gather information on Japanese movements. The Japanese battery at Cape Djoeata on Tarakan's north coast was also knocked out by USS Douglas A. Munro on 23 May. The Japanese garrison was gradually destroyed, with the survivors abandoning their remaining positions in the hills and withdrawing to the north of the island on 14 June. On this day 112 Chinese and Indonesian labourers left the Japanese-held area with a note from a senior Japanese officer asking that they be well treated. While Radio Tokyo announced that Tarakan had fallen on 15 June, the last organised Japanese resistance was encountered on 19 June and Whitehead did not declare the island secure until 21 June. Construction problems While the infantry of the 26th Brigade Group fought the Japanese in the hills, the RAAF engineers of No. 61 Airfield Construction Wing were engaged in a desperate effort to bring Tarakan's airstrip into operation. As the airstrip had been heavily damaged by pre-invasion bombing and lay in marshy terrain it proved much more difficult to repair than had been expected, and it took eight weeks and not the expected single week to restore the strip to a usable state. Extensive use was made of Marston Mat, interlocking steel plates laid down like matting. Remnants of the plates still exist in the car park at Tarakan airport. While the airstrip was finally opened on 28 June, this was too late for it to play any role in supporting the landings in Brunei or Labuan (10 June), or the landings at Balikpapan. However No. 78 Wing RAAF was based on Tarakan from 28 June and flew in support of the Balikpapan operation until the end of the war. Efforts to restart production at Tarakan's oilfields were delayed by serious damage to the facilities and Japanese holdouts, and they did not become operational until after the war. Mopping up Following the end of organised resistance the surviving Japanese on Tarakan split into small parties which headed to the north and east of the island. The 26th Brigade Group's main combat units were allocated sections of Tarakan which they swept for Japanese. Many Japanese attempted to cross the strait separating Tarakan from the mainland but were intercepted by Allied naval patrols. Allied troops also searched for