In June 1950, a military struggle between South Korea and North Korea quickly developed into a limited international war involving the U.S. and nineteen other nations. The conflict, known as the Korean War, began when the North Korean army, equipped by the Soviet Union, invaded South Korea. The UN invoked military sanctions against North Korea and the U.S. President Harry S. Truman ordered American military forces into action under the command of General Douglas MacArthur. From the beginning Truman and MacArthur had differing opinions as to how to fight the war and the ultimate outcome they hoped to achieve. While MacArthur was in command of UN operations, a period of time just under 10 months, Truman and MacArthur had several disagreements which eventually forced Truman to relieve MacArthur of his command. .
The first disagreement came over the battle at Inchon. MacArthur, a brilliant commander with an enormous ego and a supreme sense of self-confidence, demanded permission for an amphibious operation twenty-five miles west of Seoul, at Inchon. The Joint Chiefs of Staff had been opposed to the amphibious operation, warning MacArthur that Inchon had some of the highest tides in the world and that the city itself was protected by a seawall. Both of these situations would make an amphibious operation extremely hazardous. But MacArthur argued that it was precisely these conditions that would assure the element of surprise essential to the success of his operation. Since MacArthur was such a commanding and persuasive figure, and was considered by most Americans to be a great military commander, the Joint Chiefs of Staff deferred to his judgment, and the Inchon operation proved to be very successful. .
After the battle of Inchon, MacArthur was unwilling to conduct a limited war. He wanted to continue the fighting past the 38th parallel advancing all the way to the Yalu River, separating Korea and Communist China.