Just as the first watch began on the evening of 11 July 1950, a team of four Marines and four Navy gunner’s mates, led by Commander William B. Porter, executive officer of the USS Juneau (CLAA-119), transferred to the destroyer USS Mansfield (DD-728). Under way, the tin can headed for a point off the coast of North Korea, near the village of Tanchon, well north of the 40th parallel. Shrouded by darkness, the Mansfield closed to within 1,000 yards of the beach and lowered her whaleboat, then packed with Porter’s ad hoc landing party and a load of high explosives. The whaleboat shoved off, and soon the sailors and Marines were ashore, traversing precipitous terrain in complete darkness to find their target, a railroad tunnel for a major rail line that was serving as a vital supply link to advancing enemy forces. The commandos rigged two 60-pound demolition charges in the tunnel and set them to detonate when the next train passed through. Making their way back to the waiting destroyer, they were safely on board when intercepted North Korean radio broadcasts indicated that their mission had succeeded.
Lest We Forget - Sea Power in Korea
By Lieutenant Commander Thomas J. Cutler, U.S. Navy (Retired)