On 25 June 1950 , the Army of North Korea crossed the 38th Parallel and invaded South Korea , overrunning and destroying large elements of the Republic of Korea Army ; within three days , North Korea had captured Seoul . On 30 June , the United States sent Air Force , Navy , and Marine troops , along with a 1,000 man Army battalion from the 24th Infantry Division and advisers from the 1st Cavalry Division to support the ROK Army . On 18 July , the 1st Cavalry Division was ordered to Korea and landed at Pohang-dong , 80 miles north of Pusan , and 25 miles south of the communist forces . The 5th Cavalry quickly marched on Taejon and was deployed into battle position by 22 July . The next day , the men received their baptism by fire . The 8th Cavalry Regiment was swarmed by North Korean troops and the 1-5 Cavalry was sent to fill in the line . On 24 July , F Company moved to assist the overwhelmed 1-5 Cavalry on their right flank , but the numbers of North Korean troops was too much for the troopers . Only 26 men from Companies B and F escaped alive to friendly territory . Over the next few days , a defensive line was formed at Hwanggan , and the 5th Cavalry relieved elements of the battered 25th Infantry Division on the line . This line became known as the Pusan Perimeter , and the troopers held on for over 50 days against unrelenting North Korean attacks . On 9 August , 1-5 Cavalry bore the brunt of a massive enemy attack of five divisions near Taegu . Troopers of the 5th and 7th Cavalry Regiments used artillery and air support to defeat the North Koreans , and seized Hill 268 , " Triangulation Hill , " accounting for 400 enemy dead . The 5th Cavalry Regiment withstood two more large attacks , but held the perimeter . Pusan became a vital staging port for United Nations troops and materiel , and thanks to the efforts of the troops on the perimeter , enough time had been gained that now the defenders outnumbered the attackers . On 17 August , after a battle with North Korean troops , a mortar unit from H Company , 5th Cavalry was forced to surrender . The men were tied up , and 42 were shot and killed and 4-5 more were wounded ; this became known as the Hill 303 massacre
Hill 303 massacre
Hill 303 massacre
5th Cavalry Regiment