In January 1966 the US 173rd Airborne Brigade included the 1st Battalion, The Royal Australian Regiment. The brigade intended to surround and destroy the Vietcong Headquarters for the Saigon region, but by the fortunes of war the Aussies landed almost on top of the enemy headquarters, which was in an extensive tunnel network, the size and scope of which had not been found previously. This situation required extensive improvisation by the Australian infantry and engineers, but the headquarters was captured despite the best efforts of the Vietcong to defend the tunnels and the contents. The tunnel system was explored and charted, resulting in the capture of large amounts of munitions and supplies and 100,000 pages of important documents - by men willing to crawl down into the darkness armed only with a torch and a pistol, aware that the enemy could be anywhere, and that rescue was extremely difficult. Courage and determination were commonplace.