It had been two years in the planning. It required approval from Joseph Stalin, and the cooperation of Mao Tze Tung. But on June 25th, 1950, the North Korean People's Arky [NKPA], the Inmun Gun rolled south in an attempt to invade, conquer and absorb, the Republic of Korea.
Spearheaded by the 105th Brigade [t-34/85 tanks], and Soviet built prop aircraft [YAK 9s], the NKPA took Seoul in less than a week. American intervention at Taejon didn't even slow them down. But the Pusan perimeter did. And a combination of air supremacy, massive bombing, a breakout from the Pusan perimeter and the Inchon landing broke the NKPA's back, and sent them reeling north. U.N. forces under MacArthur would then move north, the Chinese would intervene, and the war would drag on for three more years. But it started on June, 25th, 1950.