The Japanese invasion force consisting of 400 transports bearing 18,700 men under the command of Konishi Yukinaga departed from Tsushima Island on May 23 and arrived at Busan harbor without any incident. The Joseon fleet of 150 ships did nothing and sat idle at port. A single vessel bearing the daimyō of Tsushima, Sō Yoshitoshi (who had been a member of the Japanese mission to Korea in 1589), detached from the Japanese fleet with a letter to the commander of Busan, Yeong Bal, demanding that the Korean forces stand down to allow the Japanese armies to proceed on towards China. The letter went unanswered, and the Japanese commenced landing operations from four o'cklock the following morning.