What would ultimately prove to be a tactical blunder by 1 ATF Command and account for the majority of Australian and New Zealand casualties throughout the war, was the laying of a minefield over a 10 km area from Dat Do to the coast. By June 1967, close to 23,000 "jumping jack" mines had been laid by the Australian engineers within a 100-metre-wide strip of cleared ground between a double row of fences. Security of the minefield proved to be ineffective and the VC thereafter simply uplifted the mines and re-used them against the Australians and New Zealanders.