The surrender of Japan was inevitable after the United States dropped the first atom bomb on Hiroshima in August of 1945. Stalin was waiting for just such an opportunity where the Soviets could enter the war against Japan while incurring minimal loss, and so it was no surprise when he declared war against Japan after the United States dropped the second atom bomb. Upon Japanese surrender on August 15, 1945, Soviet military forces swept through Manchuria and North Korea taking over Japanese control over these provinces. The United States reacted in alarm when she realized the potential danger of having the strategic Korean peninsula controlled by Communist forces. President Truman proposed a joint occupation of Korea by the two powers where the Soviets would occupy the territory north of the 38 parallel, while the United States would control the area south of the line.

Initially it was the intention of both sides to establish a stable and unified Korea in order to withdraw their military forces from the area. However, neither the Soviet Union nor the United States wanted the peninsula to fall into the other's hand. In short, the Soviets and the U.S. desired to withdraw their military and resources out of Korea, but they also wanted to leave behind a nation that was favorable to each country's ideology; the Soviets desired a Communist Korea whereas the U.S. wanted a democratic nation to be established. And so the roots of division were laid from the very onset of Korea's liberation.

Communist elements in the north were present during the Japanese colonial period, but with the north now under Soviet tutelage, the leftist factions were able to seize power. During the period of civil turmoil of 1945-1946, there were many different leftist factions vying for power. It was during this time that the Soviets helped establish Kim Il Sung, a product of the Soviet military machine, as the leading political figure in the north.

In the south, an entirely different story unfolded. The KPR (Koreans People's Republic), which was very leftist in nature, attested that they were the political voice of the Korean people. However, the primary aim at the time was to prevent communist takeover of South Korea, so the KPR was banned. During this time, a Korean patriot named Syngman Rhee began to acquire political power among the conservative elitists in South Korea. His dogmatic advocacy for Korea's full independence often caused friction between him and U.S. officials. But due to Rhee's strong stance against communism, and because of his commitment to maintaining civil order during these turbulent times, General Hodge had no other choice but to give his support to Rhee. Therefore, with U.S. support and the use of strong-arm tactics, Syngman Rhee eventually positioned himself as the dominant political leader in South Korea by 1947.

Although two different political governments had emerged in Korea by 1947, the fact that they were still only provisional governments, gave the Korean people hope for a possible unification. Up until this time, nationalist from both the North and South continued their efforts to negotiate a unification treaty, however, irreconcilable differences between the U.S. and the Soviet Union prevented any such goal. Eventually, the U.S. concluded that the chasm that existed between the U.S. and the Soviet Union in establishing a unified Korea was insurmountable and so they pressured the United Nations to allow for a general election in Korea. Suspicious of foul play by the United States, the Soviets refused to allow the election to be held in North Korea. Nevertheless, the U.S. advocated that voting should still be aimed out in the south in order to establish some sort of legitimate government, and so in May 1948, South Korea held its first general elections.

Soon thereafter, the Republic of Korea (ROK) was established and was promptly recognized by the U.N. as the legitimate government of Korea. Up until and through these elections, there were heavy protests by Korean leftists who feared that these elections would kill all chances for unification. During the same time, the north followed with similar actions by holding its own elections. When the votes were tabulated, the Soviet Union and other communist countries declared Kim Ii Sung president of the new Democratic People’s Republic of Korea (DPKR), which was immediately recognized, as the legitimate government of North Korea. By winter of 1948, the worst fears of Korean Nationalists were confirmed as Korea became permanently divided at the 38th parallel.

The elections of 1948 and the division of Korea that ensued set the stage for a civil war. And by 1950, both North and South Korea sensed that war was inevitable. Not only were their armies getting prepared for war, but both Syngman Rhee and Kim Ii Sung declared on several occasions that military force would be necessary to unify Korea. However, in terms of being prepared for war, North Korea had a clear advantage over the south. Not only did North Korea possess a larger army, it also had many experienced veterans who had fought in China's Civil War. In addition, North Korea, by this time, was manufacturing some of their own weapons as well as possessing many Soviet-made weapons. South Korea, on the other hand, had soldiers who had not even attended basic training. Finally, North Korea had the support of the Chinese military. Therefore, in light of North Korea's military advantage on the eve of the war, it is reasonable to assume that it was North Korea that fired the first shot on June 25, 1950 that started the Korean War.

On September 16, 1950, the 1st Marine Division Band made the Inchon landing as part of the 1st Provisional Marine Brigade with Major General Oliver P. Smith, Division Commander, and then took over the duty of guarding Major General Smith's command post. After a few moves, the band made the Wonsan landing and then half of the band was pulled off the security detail to help unload and sort supplies landed at Wonsan. The band remained split, half staying with General Smith at the rear command post, and the other half moving through North Korea guarding the forward command post of Lieutenant General Edward Craig. At the Chosin Reservoir, the latter group engaged in heavy fighting. One bandsman was killed and seven were wounded, not including the frostbite cases.

The Korean War resulted in an estimated 4,000,000 casualties, including civilians. The war ended inconclusively in July 1953, but not before it established a precedent for United States intervention to contain communist expansion.