The Weapon That Smashed North Korea's Whole Plan

I don't much care for the narrator's ominous tone, but this video, at least, tells a pretty good story about the beginning of the Korean War. I didn't realize just how much territory the North had overrun before they were stopped. A good story? Make it a pretty amazing story: a ship with a big gun can defeat a horde of maniacs who don't have a big gun. Sounds kind of like the story of the British Empire.

ROKS Bak Du San (PC-501) being rearmed in Hawaii, March 1950
Link goes to Wikipedia page about the Battle of Korea Strait

The mast from the Bak Du San is now a memorial at the Korean Naval Academy.

South Korea. Busan is on the SE corner.
The long, thin island just offshore is the Japanese island Tsushima.
It sits in the middle of the Korean Strait, half way to the main Japanese island.