Korean War two years of fighting became a war of attrition, with the front line close to the 38th parallel. The war in the air, however, was never a stalemate. North Korea was subject to a massive bombing campaign. Jet fighters confronted each other in air-to-air combat for the first time in history, and Soviet pilots covertly flew in defense of their communist allies. The fighting ended on 27 July 1953, when an armistice was signed. The agreement created the Korean Demilitarized Zone to separate North and South Korea, and allowed the return of prisoners. However, no peace treaty was ever signed,
Canada in the Korean War in the objective that it had set with the United Nations forces. In April 1951, Chinese forces of the 118th Division attacked the Kapyong Valley in force, and pushed South Korean and New Zealand troops into retreat. Under heavy pressure, the Korean 6th Division broke, and the line collapsed. American and South Korean men poured through a gap under protective covering fire from Australians who were holding their section of the line despite heavy pressure. The 3rd Battalion, Royal Australian Regiment (3 RAR) and 2nd Battalion, Princess Patricia's Canadian Light Infantry (2 PPCLI) were ordered to halt this Chinese advance.