During the invasion, a North Korean steamer was assigned to insert troops along the peninsula's southeastern coast.

[3] The merchant ship of 1,000 tons was armed with machine guns and loaded with 600 soldiers of the 766th Independent Infantry Regiment.

[4] It was early morning when the Republic of Korea Navy submarine chaser ROKS Pak Tu San spotted the lone enemy steamer eighteen miles from Busan.

[5] After the North Koreans began taking hits, they attempted to flee the engagement, but were chased by the Bak Du San in a running battle that ended with the steamer being sunk near Tsushima Island, with heavy loss of life.

Busan was vital but only lightly defended, and if it had fallen the North Koreans would have been one step closer to completely overrunning the country.