The Korean War began on 25 June 1950 with a massive North Korean invasion of South Korea which nearly overran the country.
During the invasion, a North Korean steamer was assigned to insert troops along the peninsula's southeastern coast.
The merchant ship of 1,000 tons was armed with machine guns and loaded with 600 soldiers of the 766th Independent Infantry Regiment.

It was early morning when the Republic of Korea Navy submarine chaser ROKS Bak Du San spotted the lone enemy steamer eighteen miles from Busan.
The chaser, also formerly American, was the lead vessel of the South Korean Navy.

Bak Du San first challenged the steamer with signal lights and received no response.
But when the South Koreans turned on their searchlights, the North Koreans opened fire, hitting the Bak Du San's bridge.
The helmsman was killed and the officer of the deck seriously wounded.
Bak Du San returned fire with her main 3-inch anti-aircraft gun and six .50-caliber machine guns.
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.

The victory was a major strategic gain.
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.
The Korean War began on 25 June 1950 with a massive North Korean invasion of South Korea which nearly overran the country. During the invasion, a North Korean steamer was assigned to insert troops along the peninsula's southeastern coast. The merchant ship of 1,000 tons was armed with machine guns and loaded with 600 soldiers of the 766th Independent Infantry Regiment.
It was early morning when the Republic of Korea Navy submarine chaser ROKS Bak Du San spotted the lone enemy steamer eighteen miles from Busan. The chaser, also formerly American, was the lead vessel of the South Korean Navy.
Bak Du San first challenged the steamer with signal lights and received no response. But when the South Koreans turned on their searchlights, the North Koreans opened fire, hitting the Bak Du San's bridge. The helmsman was killed and the officer of the deck seriously wounded. Bak Du San returned fire with her main 3-inch anti-aircraft gun and six .50-caliber machine guns. 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.
The victory was a major strategic gain. 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.
Battle of Korea Strait