June 25, 1950:
North Korea invades South Korea with the help of the Soviet Union and it's army. Because South Korea was completely unprepared, the North Koren Communists easily made their way through the southern part of the country.
This was important because it was the first act of warfare in the long, treacherous battle that eventually left many lives lost.
June 28, 1950:
North Korea invades and captures the captial city of South Korea, Seoul.
This was critical to the Communist offensive because this was a massive win for North Korea. When a capital city falls, this usually means that the entire country has fallen to the enemy.
September 27, 1950:
Truman authorizes the U.S. Troops to invade North Korea in efforts to push back the Communist army into their own territory. This was his attempt to quash any hopes of another North Korean offensive.
This was important because it revealed how the tide was turning in the Korean War towards the side of the democratic South Korean army and with the aid of American forces.
April 9, 1951:
General MacArthur is fired by Present Harry S. Truman. MacArthur was fired because he wanted to launch a nuclear attack against China, who was aiding the North Korean forces throughout the Korean War.
This was important because it showed that the president was not willing to go to extreme lengths to win the war, unlike the last time. Truman did not want to repeat the mass slaughter in China like they did in Japan.
July 27, 1953:
The UN and North Korea make an agreement to have an armistice to end the fighting in the war. This occurred after over two years of peace talks between the nations trying to end the war.
This finally ended the war, which was much needed. The 38th parallel was reinstated and it was a demilitarized zone so that the two Korean nations would never fight again.