Korean War: Task Force Smith: American and North Korean forces first clash, in the Battle of Osan.

The Korean War was an armed conflict on the Korean Peninsula fought between North Korea and South Korea and their allies. North Korea was supported by China and the Soviet Union, while South Korea was supported by the United Nations Command (UNC) led by the United States. The conflict was one of the first major proxy wars of the Cold War. Fighting ended in 1953 with an armistice but no peace treaty, leading to the ongoing Korean conflict.

The Battle of Osan was the first engagement between the United States and North Korea during the Korean War. On July 5, 1950, Task Force Smith, an American task force of 540 infantry supported by an artillery battery, was moved to Osan, south of Seoul, the capital of South Korea, and was ordered to fight as a rearguard to delay the advancing North Korean forces while more US troops arrived to form a stronger defensive line to the south. The task force lacked both anti-tank guns and effective infantry anti-tank weapons and had been equipped with obsolete rocket launchers and a few 57 mm recoilless rifles. Aside from a limited number of HEAT shells for the unit's 105 mm howitzers, crew-served weapons that could defeat T-34/85 tanks from the Soviet Union had not yet been distributed to the US Army forces in South Korea.

North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia. It constitutes the northern half of the Korean Peninsula and borders China and Russia to the north at the Yalu (Amnok) and Tumen rivers, and South Korea to the south at the Korean Demilitarized Zone (DMZ). The country's western border is formed by the Yellow Sea, while its eastern border is defined by the Sea of Japan. North Korea, like South Korea, claims to be the sole legitimate government of the entire peninsula and adjacent islands. Pyongyang is the capital and largest city.