purchased a 600-ton submarine chaser, the former on the American civil market with funds raised among its personnel. She was renamed as ROKS Baekdusan (PC 701) after Paektu Mountain, and became "the first significant warship of the newly independent nation" (Later on the first night of the Korean War, she sank a 1,000-ton North Korean freighter loaded with 600 troops toward the vital South Korean port of Busan.). The Navy purchased three additional PC-461-class submarine chasers before the Korean War. On April 15, 1949, the Republic of Korea Marine Corps (ROKMC) was founded at Deoksan airfield in Jinhae. The Marine Corps carried out Suppression Operations against communist elements in Jinju and Jeju Island. Korean War and 1950s The Korean War started with the North Korean army's surprise attack on Sunday, June 25, 1950. The infant ROK Navy confronted threats from the stronger North Korean navy: "Perhaps the most aggressive and effective, if smallest, member of the South Korean armed services during the first year of the Korean War was the Republic of Korea Navy. At the outset of the conflict, the 6,956-man ROKN, with [33] naval vessels of various types, was outnumbered by the 13,700 men and 110 naval vessels of the North Korean navy." With its UN allies, dominated by U.S. forces, the ROK Navy was able to gain control in the seas surrounding the country; the ROK Navy secured the seas south of the 38th parallel. After the Incheon landing, the ROK Navy proceeded to take control of the entire seas surrounding the Korean peninsula, as a task group (Task Group 95.7) of the UN Blockading and Escort Force (Task Force 95). When UN troops withdrew from the north, due to the entry of Chinese troops, the ROK Navy conducted evacuation operations for the UN troops and Korean refugees with the UN allies. On July 27, 1953, the three-year-long war was brought to an end when an armistice agreement was signed. During the war, Australia, Canada, Colombia, France, the Netherlands, New Zealand, Thailand, the United Kingdom, and the United States contributed naval vessels as UN allies; Denmark sent the hospital ship Jutlandia. During the Korean War, the ROK Navy acquired 28 ex-USN ships including five Tacoma-class frigates. The Mutual Defense Treaty between South Korea and the United States was signed on 1 October 1953. In 1955, the South Korean government and the United States government made an agreement