The objectives of the North Koreans' offensive was divided into three lines. The aim of the first one was to pass Gaeseong, Munsan and Seoul. The second was to pass Uijeongbu and Seoul and the goal of the third was to pass Chuncheon. Of these three lines, the Chuncheon line's advance ground to a stop, but the Gaeseong-Munsan line, after a 1-day delay, broke through and the Uijeongbu line broke through easily.
The North Koreans had two divisions (3rd and 4th) reinforced with one tank brigade (105th), and the South Koreans had one division (7th). The North Koreans, armed with Russian T-34 tanks, couldn't be stopped even by the added men of 2nd South Korean division with the Water security brigade.
The South Korean 7th Division was pushed down from the front line, and established a defence line linking Pocheon and Dongducheon. This couldn't hold, and the division was pushed backed to Uijeongbu. Chae Byeong-deok, the Chief of Staff of the South Korean Defence Corps, added the 2nd Division and other men, but the next day the North Koreans pushed into Uijeongbu.
As a last resort, the South Koreans established another defence line at Gangbuk-gu, but were defeated at the Battle of Miari. After three days of resistance, the North Koreans drove into Seoul.