This Battle occurred just after the replacement of General Douglas MacArthur by General Mathew Ridgeway as the commander of the UN forces in Korea. Australian (Royal Australian Regiment- 3rd Battalion), British(1st Battalion Middlesex Regiment, 1st Battalion Argyll and Sutherland Highlanders, New Zealand forces and Canadian (2nd Battalion Princess Patricia's Canadian Light Infantry) forces had been combined into the 27th Commonwealth Brigade and had already seen action in the war. In mid-May they had been moved into reserve for a rest as constant advances had been taking place along the front and the Brigade had just fought in the Battle of Maehwa-San.
In April of 1951 the Chinese launched what was known as the Spring Offensive and quickly began to force UN units back. One of the points of retreat was through the Kap'yong valley where the South Korean forces were retreating between to large escarpments towards Seoul to the south. The Canadian and Australian Battalions took up positions on each side of the valley to support the retreating forces. On the night of April 22nd the Chinese forces began to try and infiltrate the Australian positions on hill 504. Heavy fighting ensued and eventually the Australian forces where pulled back to new defensive positions. The Chinese than turned their attentions t the Canadians on Hill 677 and once again launched a fierce night attack which failed to dislodge the PPCLI. A breakthrough of the UN forces had been prevented and the Chinese division withdrew back up the valley as the offensive ground to a halt.