Well-trained and equipped, the North Korean People’s Army swept rapidly south in the first phase of the Korean war. In contrast, the South’s Republic of Korea forces were often disorganized and inclined to flee the battle field.

July 5, 1950
The first U.S. Marines – leading the U.N. forces – joined battle shortly after landing on the Korean Peninsula. U.S. troops suffered heavy casualties and the four American divisions were driven back into a perimeter around the southern port city of Pusan.