After capturing Busan and Dongnae, the Japanese army under Konishi Yukinaga advanced at a rapid rate of almost 20 kilometers per day towards the Joseon capital of Hanseong (present-day Seoul) .
On receiving his formal assignment to block the Japanese advance from Busan towards Hanseomg while he was still in Gyeongsang Province, he found that his company of 300 supposedly first-rate troops consisted largely of untrained students and clerks conscripted out of government offices to replace men whose names were on the military lists, but who were either missing, already deceased, or claiming exemption due to illness.
On arriving in Sangju, he found that the garrison was completely depleted, as all of the soldiers had been called away to defend the provincial capital of Daegu to the south.
With no soldiers, Yi decided to use grain from the government warehouses to recruit local peasants, and managed to gather a force of 900 men.
He continued through the strategic Choryong Pass, which could have been held to good effect against the Japanese, and joined his superior, General Sin Rip at Chungju.