USS Barb (SS-220), Cdr Eugene Fluckey commanding, began its twelfth war patrol on 8 June 1945 departing Pearl Harbor. The patrol area included the northern shore of Hokkaido and the southern shores of Sakhalin, which at the time was divided between Japan and the USSR at the 50°N parallel. Before the events answering the OP’s question, Barb became the first U.S. submarine to perform a rocket artillery bombardment on the night of June 21-22. Twelve 127mm rockets were fired from a fixed-mount Mark 51 launcher at the town of Shari on the northern coast of Hokkaido.

As related in Fluckey’s book about USS Barb, “Thunder Below,” while patrolling Sakhalin’s coast railroad tracks were found to run close to the shoreline, presenting a sabotage opportunity. A 55-pound scuttling charge was thought sufficient to destroy tracks while a train was traversing them, but the method of detonating the charge remained elusive. Engineman 3rd Class Billy Hatfield provided the solution, remembering his childhood in Ohio when he would use trains to crack nuts as the rails sagged under the train’s weight. A micro switch placed under a rail would have the train itself set off the demolition after the saboteurs were safely returned to the Barb.

The 12th Patrol Action Report has first mention of this plan on 19 July while patrolling Patience Bay, the large semi-circular basin on Sakhalin’s eastern coast. “Our plan is to locate a suitable coastal position of the railways, land our SABOTEUR force and plant a 55 lb. demolition charge under the tracks. Then this charge will be exploded by a train passing over and closing the micro switch.” More entries on the 19 July and 20 July mention train sightings. On the evening of 20 July the entry at 1947 reads: “Sighted regular train. Previous observations have given us their time tables now. Selected optimum position for landing … Sandy beach, no houses within 700 yards of spot and submarine could approach 1000 yards from beach without grounding.” They were foiled by clear skies and bright moonlight on the nights of 20 and 21 July, but the weather was right on 22 July.

The plan is detailed in the Action Report as follows. Two rubber boats with eight men will make for shore. Two men will stay with the boats including a signalman. Three will go north and south and inland from the tracks as sentries, and three will set the charge. A roadway must be crossed between the shore and the railroad. The saboteurs are: Chief Gunners Mate Paul G. Saunders, USN; the designer of the detonator Billy Hatfield, USNR; Signalman 2nd Class Francis Neal Sever, USNR; Ship’s Cook 1st Class Lawrence W. Newland, USN; Torpedoman’s Mate 3rd Class Edward W. Klingesmith, USNR; Motor Machinist’s Mate 2nd Class James E. Richard, USN; Motor Machinist’s Mate 1st Class John Markuson, USN; Lt. William M. Walker, USNR. “Thunder Below” includes the criteria for selection: unmarried, a mix of Naval and Naval Reserve, representation from all ship departments, and Boy Scouts preferred. Fluckey was an Eagle Scout and knew that the wayfinding and first aid training the other Scouts would have might prove useful. Fluckey himself was prevented from leading the party.

The Action Report reveals how those remaining on Barb saw the plan go awry. First, two small coastal boats transited the target area and delayed the launch of the boats by 55 minutes. Fluckey tells the departing sabotage team, “If you get stuck, head for Siberia [sic] 130 miles north – follow the mountain ranges, good luck.” It took 30 minutes for the party to reach the beach. Twelve minutes later, an unscheduled train approached from the south! The party was undetected, completed their task, and launched off the beach 57 minutes after landing. Thirteen minutes later, at 0145 on 23rd July: “Ye gods: another northbound train coming up the tracks! Broke the silence to yell at the boats, ‘Paddle like the devil!’” But even so, the boat crews wait with everyone else to see what happens. Two minutes later: “WHAM!! What a thrill! What a beautiful sight! The charge made a much greater explosion than we expected, the engine’s boiler blew, wreckage few two hundred feet in the air in a flash of flame and smoke, cars piled up and rolled off the track in a writhing, twisting mass of wreckage. Cheers!” The saboteurs were picked up at 0151 and by 0202 Barb was in deep water again.

Debriefing revealed more snafus. The navigation was off by 500 yards and they landed in a house’s back yard, fortunately without alerting any dogs. The fields seen from offshore was not grassland but full of waist-high rushes that made stealth impossible. Deep, invisible ditches on each side of the roadway added comic relief. Once they arrived at the sabotage location, one was dispatched to investigate a strange shape nearby. He returned to say in alarm, "It’s a lookout tower!" Concerned by the noise of their tools, they dug with their hands “dog-fashion.” The first train came upon them suddenly, not noticed until it was 75-100 yards away. Each member of the party was sure that the train engineer looked at them personally. Hatfield’s CO2 cartridges for his lifebelt went off in the dive for cover, making him initially think he’d been shot. In their haste the switch was given less clearance below the rail than planned. They were two-thirds of the way back to the Barb when they had a front-row seat for the train’s destruction. The Action Report does not make any mention of pursuit of Barb following the demolition, and the rest of 23 July was spent preparing for another rocket attack that evening.

This shore party is the only known instance of Allied troops landing on the Japanese Home Islands during the war.

Sources:

USS Barb (SS 220), Report of Twelfth War Patrol by Eugene Fluckey, commanding. File SS220/a16-3, Serial 043, read from microfilm reel G-108-AR-162-75, NNPSO Naval District Washington Microfilm Section.

Thunder Below! The USS Barb Revolutionizes Submarine Warfare in WWII by Adm. Eugene Fluckey, 1992, University of Illinois Press