High Quality Content by WIKIPEDIA articles! The Battle of Masan was an engagement between United Nations (UN) and North Korean (NK) forces, which took place early in the Korean War between August 5 and September 19, 1950, in the vicinity of Masan and the Naktong River in South Korea. It was part of the Battle of Pusan Perimeter, and was one of several large engagements fought simultaneously. The battle ended in a victory for the UN after large numbers of United States (US) and Republic of Korea (ROK) troops were able to repel the repeated attacks of two North Korean divisions.