The Submarine That Sank a Train ...

The USS Barb was a Gato-class submarine operated by the United States in the Pacific Ocean during World War II. Under the leadership of Commander Eugene B. Fluckey, who would be awarded a Medal of Honor and 4 Navy Crosses for his exploits, the crew of the Barb devastated Japanese shipping during its patrols. The book Medal of Honor describes one of those incredible feats:

Early in 1945, the Barb was moving along the China coast, looking for targets of opportunity. On January 8, it sank a large Japanese ammunition ship it had been stalking for hours. Believing a larger group of enemy ships was in the area, by January 25, Fluckey had located this “mother lode,” as he called it: a convoy of more than thirty Japanese ships anchored in Mamkwan Harbor. The harbor was shallow and heavily mined, with threatening rock formations. It was clear that if the Barb got close to attack, it would require a nearly impossible run at full speed through uncharted mine- and rock-obstructed waters to make a successful escape. Fluckey immediately ordered an attack anyway.
He managed to penetrate the perimeter of frigates designed to protect the anchored ships from submarines. In water of only thirty feet deep, he maneuvered to within range and launched four torpedoes from the forward tubes, then fired four more from the rear tubes. After watching eight direct hits on six main targets—including another ammunition ship whose explosion damaged craft all around it—he turned the Barb around and headed for open sea. With Japanese shells hitting all around it, the Barb had to stay on the surface for almost an hour before reaching waters deep enough to dive.

But the crew of the Barb wasn’t done being spectacular. That summer, the Navy modified the Barb so that it could launch rockets—the first such American submarine. The Barb used these to attack an air station and factories in Japan.

Perhaps their most daring attack at the Japanese Empire came toward the end of the war when the crew of this submarine attacked a train in Karafuto Prefecture—what we now call the southern end of the Russian island of Sakhalin.

On July 23, 1945, the Barb approached the coast, sank a frigate, then surfaced about 950 yards offshore. 8 volunteers paddled ashore in rubber boats and walked 400 yards to a set of railroad tracks. They rigged explosives to the tracks, then returned to the Barb. As they paddled back, a 16-car military train passed by, activated the explosives, and blew up.
The Barb was mothballed in 1947, reactivated in 1951, then loaned to the Italian Navy in 1954, before finally being scrapped in 1975. Commander Fluckey stayed in the Navy after the war, eventually reaching the rank of Rear Admiral. But by his own account, his greatest accomplishment was keeping everyone on his ship safe:

No one who ever served under my command was awarded the Purple Heart for being wounded or killed, and all of us brought our Barb back safe and sound.