Vietnam ground combat operations in 1965, and at their peak they numbered more than 500,000. The US also engaged in a sustained aerial bombing campaign. Meanwhile, China and the Soviet Union provided North Vietnam with significant material aid and 15,000 combat advisers. Communist forces supplying the Việt Cộng carried supplies along the Hồ Chí Minh trail, which passed through the Kingdom of Laos. The communists attacked South Vietnamese targets during the 1968 Tết Offensive. Although the campaign failed militarily, it shocked the American establishment, and turned US public opinion against the war. During the offensive, communist troops massacred over 3,000 civilians
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.