1969 the main effort of the task force returned to Phuoc Tuy Province. One operation which became infamous as it became known to the public was Operation Mundingburra, a mine-clearing action conducted in the Long Hai Hills from 15 July 1969 involving 6 RAR/NZ (ANZAC.) The operation had three objectives: disrupt enemy infiltration into the villages, maintain regular checkpoints on the main access routes between the villages, visit local hamlets and offer medical services to those villagers who might need it. All platoons conducted mine clearing and ambushing tasks. After 31 days the operation ended with casualties all from mine detonations. These were Australian mines which had been uplifted by the VC from the Australian minefield laid in 1967 and relaid or booby trapped. 6 RAR/NZ's casualties were 11 killed (6 New Zealanders, 5 Australians) and 54 wounded (10 New Zealanders, 44 Australians). A particularly disastrous incident on 21 July was the major inspiration for the 1983 pop song I Was Only 19 by the Australian band Redgum. One of the most successful 1 ATF operations which severely weakened the PAVN/VC forces in 1 ATF's area of operations was Operation Marsden (3–28 December 1969) which was a search-and-destroy mission conducted in the Mây Tào Mountains where the VC 5th Division was headquartered. The VC base in the mountains provided logistics and controlled the VC 274th and 275th Regiments as well as local VC guerilla forces. The area was also the location of the K76A Hospital, which was the principal provider of medical services for the regional VC and PAVN forces. All five infantry companies from 6 RAR/NZ were deployed on 2 December. A Company scaled the mountains, having to make their way through a 200-metre-wide minefield of improvised mines made from unexploded U.S Air Force cluster bombs. On 8 December, D Company located the first major stores dump in a cave at the south of the mountains. It contained approximately 2,500 anti-personnel grenades, 22 anti-tank mines, 22 boxes of anti-watercraft mines and a large quantity of weapons, equipment and explosives. On the same day, B Company, on the north side of the mountain, found the first signs of the hospitals. The following day they discovered a bunker system of 12 bunkers identified as part of K76A Hospital. On 11 December V Company, operating in the south-east, located another hospital with 17 large bunkers large enough to take up to 100