When their fifth offensive failed in May 1951 the communists abandoned a war of movement and engaged the United Nations Command (UNC) in positional warfare...
Limited advances against heavily fortified positions, intense artillery bombardments, trench fighting, minefields, barbed wire and aggressive patrolling characterised this phase of the Korean War.
The first clashes were initiated by the UNC attempting to eliminate tactically important enemy-held positions. From 18 August to 5 September 1951 South Korean (ROK) and US forces assaulted hill 938 then held by North Korean (KPA) troops. In what became known as the battle for Bloody Ridge the UNC captured the objective at the cost of 2,700 casualties. KPA losses were estimated to be 14,000. From 13 September to 15 October the 2nd US Division launched a series of assaults against the KPA occupying Heartbreak Ridge. Very heavy fighting resulted with US and French troops eventually capturing the heights at the cost of 3,700 casualties. KPA and Chinese (CPV) losses were 22,000.
Fighting 'seesaw battles' to contest selected terrain features was a deliberate tactic employed by the CPV. Beginning late in 1951 the ten-month struggle for a treeless mountain known as Old Baldy saw the mountain change hands several times. In the battle for Whitehorse Mountain, from 6 October to 15 October 1952, the objective changed hands twenty-four times before the UNC finally secured it. The battle for Hill 598 in the Triangle Hill area was as severe. The UNC was defeated and lost 9,000 casualties in 42 days.
By January 1953, 758,000 UNC troops faced 1,100,000 communist troops along a front line which had changed very little since May 1951. Peace negotiations were nearing a conclusion but the communists, determined to win the political and psychological contest, intensified their military efforts. Through the first months of 1953 communist assaults steadily increased in intensity and size. In June three CPV divisions drove ROK troops back five kilometres. On 6 July the communists launched their most ambitious offensive since May 1951 and by 11 July had captured Pork Chop Hill. On 13 July six CPV divisions struck south of Kumsong pushing ROK troops back 13 kilometres. UNC counterattacks won back some of the ground lost before the armistice came into effect at 2200 hours on 27 July 1953. The Hook was the site of four major clashes between the UNC and the CPV in 1952–1953. The final battle for the Hook, which involved 2RAR, occurred only a day before the armistice came into effect.
The last two months of the war was one of its most bloody periods. It cost 53,000 UN and 105,000 communist casualties, the majority inflicted by artillery. In this same period over 700,000 communist artillery rounds hit UNC positions and 4,900,000 UNC artillery rounds were fired in response.