The United States has fought in many wars throughout history. Whether the fighting took place in Europe, as during the First World War, or in our homeland, as during the Civil War. The one war that many people seem to forget is the Korean War. The Korean War, also known as the "Forgotten War", was a war between North Korea, South Korea, and the United States along with help from the South Koreans. The Korean War was fought on sea, on land, and in the air on and near the Korean Peninsula (Brown, p.2). On June 25, 1950, the North Koreans crossed the thirty-eighth parallel. The invasion was successful because the South was not expecting or even preparing for war. The invasion was so successful that they pushed the south into a small defensive area around Pusan. That's when President Truman quickly intervenes to stop the North Koreans from invading. Truman ordered General Douglas MacArthur's American military to support South Korea. The Korean War was a clash between communist forces and those of the free world (Brown, p.2). On June 25, 1950 at 4 am the North Korean People's Army (KPA) attacked across the 38th parallel, implementing a well-developed invasion plan ( Lewis p.1). The KPA had a huge number of military personnel compared to the South Koreans. It had approximately 135,000 soldiers in 10 divisions, five separate infantry brigades, and one armored brigade with 120 Soviet-made T-34 tanks (Lewis p.1). The Republic of Korea (ROK) was caught by surprise and was not fully equipped with weapons like the KPA (Lewis p.1). So anyway the ROK couldn't stop the invasion. But if the South Koreans had had heavy artillery like the KPA, perhaps the KPA's invasion plan would have been a failure. The UN Security Council passed a US-sponsored resolution calling for…half of the document… (Brown, p.17). On October 7, the United Nations General Assembly passed a resolution calling for the unification of Korea and authorized MacArthur to send his forces into North Korea. The North Korean capital Pyongyang fell on October 19 and allied United Nations troops invaded the North without encountering any opposition. They pushed North Korean forces toward the Yalu River, which formed North Korea's border with the China region. The war left its mark on the Korean Peninsula and the world around it. Even though the Korean War was quite short, no one knows the exact number of deaths. According to the History Channel website, “nearly 5 million people died and nearly 40,000 Americans died in action along with more than 100,000 wounded.” (Korean War, p.1) Every war will have its cost. The approximate total of US involvement in Korea was approximately 67 billion (Heat, p.2).