Operation Crimp Westmoreland requested further reinforcement and US and allied forces increased to 44 battalions which would be used to directly bolster the ARVN. Australia's growing involvement in Vietnam reflected the American build up. In 1963, the Australian government had committed a small advisory team, known as the Australian Army Training Team Vietnam (AATTV), to help train the South Vietnamese forces. However, in June 1965 the decision to commit ground troops was made, and the 1st Battalion, Royal Australian Regiment—originally commanded by Lieutenant Colonel Ivan 'Lou' Brumfield—was dispatched. Supporting 1 RAR was 1 Troop, A Squadron, 4th/19th Prince of Wales's Light Horse
What Happened to Us a "mid-tempo duet ballad" which signifies Mauboy's strength as a global player. On 21 March 2011, "What Happened to Us" debuted at number 30 on the ARIA Singles Chart, and peaked at number 14 the following week. The song was certified platinum by the Australian Recording Industry Association (ARIA), for selling 70,000 copies. "What Happened to Us" spent a total of ten weeks in the ARIA top fifty. The music video for the song was shot in the Elizabeth Bay House in Sydney on 26 November 2010. The video was shot during Sean's visit to Australia for the Summerbeatz tour.