On 25 June 1950, the North Korean Army invaded South Korea, starting the Korean War.  The UN organized a multinational police force to defend South Korea.

On 7 August 1950, the Canadian government authorized sending soldiers, including 2 RCHA.  A train carrying 2 RCHA Gunners met with tragedy on 21 November 1950.  Seventeen soldiers died in the Canoe River Disaster.

Canadian Army units fought well at Kapyong and other battles.  Naval and air assets also played important roles.  In May 1952, 1 RCHA replaced 2 RCHA in South Korea.  The 81^st Field Regiment, RCA, later named 4 RCHA, took over for 1 RCHA in April 1953.  On 27 July 1953, the fighting stopped with the signing of the Korean Armistice Agreement.

Over 25,500 Canadians served in the Korean theatre by the time of the armistice.  A total of 516 Canadians lost their lives, including 13 Gunners.