He was joined at Chungju by Gyeongsang Provincial Governor Kim Su, who had previously collected a large force at Daegu while waiting for a general to be sent from the capital, Hanseong (modern day Seoul).
Sin Rip was en route to the Choryeong Stronghold to block the Choryeong Pass which the Japanese would have to use to move north when he learned that Yi Il's forces had been routed at Sangju by Konishi Yukinaga's First Division and that General Yi had fled, he decided to remain at Chungju and fight the Japanese on level terrain to better employ his cavalry.
Sin selected a large, natural amphitheater at a place called Tangeumdae (탄금대), with mountains at one side and a curving river at the other to make his stand.
Apparently Sin chose this site thinking to best employ his cavalry against a Japanese enemy that was predominantly infantry.
Suddenly aware of their tactical disadvantage, many of the Korean forces broke ranks and frantically tried to escape through one or the other of the passages, but were either cut down by the Japanese or drowned in the river.