Answer:
The battle that was a major turning point for US and Korean forces during the Korean War was the Battle of Pusan Perimeter.
Step-by-step explanation:
The Battle of the Busan Perimeter was fought during the Korean War between August 4 and September 15, 1950, between American and South Korean forces on the one hand and the North Korean People's Army on the other. The Busan Perimeter was an area in the extreme southeast of Korea, which was the only territory that wasn't occupied by the North Korean troops. The defensive line, called "Perimeter", extended for about 225 km and was named after the coastal city of Busan. Until the landing and subsequent counterattack by the UN forces at Incheon, the Busan perimeter served as the last line of defense against the North Korean advance south and an important bridgehead for supplies and reinforcements.
By August 1, the forces of South Korea and the United States retreated to Busan. The rest of the controlled territory, which amounted to no more than 10% of the former territory of the Republic of Korea, was called the Busan Perimeter. From late July to September 1950, American and South Korean troops fought defensive battles for the right to preserve the last territory on the peninsula. The defenders managed to maintain a foothold, which saved the entire result of the Korean War for the southerners and saved them from complete defeat and destruction.
The threat to the Busan perimeter was eliminated after the Incheon landing operation of the US armed forces, which began on September 15, 1950. On September 23, Seoul was recaptured by the Americans.