[66] X Corps Operation Instruction (OI) 11, 14 Oct 50; Smith, Notes, 385.
It was this tactical scheme, then, that prevailed as the Marines departed Inchon from 15 to 17 October and the 7th Infantry Division prepared to embark from Pusan. General Smith, of course, placed into effect his alternate order for a landing on RED Beach.[67] While there may be a note of humor in the fact that on 15 October ComPhibGruOne issued his OpnO 16-50 for the “assault landing” at Wonsan, it must be remembered that the ship-to-shore movement would remain essentially the same from the Navy’s standpoint, regardless of the swift march of events ashore.
[67] According to General Smith, “The reason for issuing 1stMarDiv OpnO 17-50 was to provide for an administrative landing in sheltered waters just north of Wonsan where there would be easy access to the existing road net. The ship-to-shore movement provided for in 1stMarDiv OpnO 16-50 was retained intact. This plan [OpnO 17-50] had to be dropped when it was found that Wonsan Harbor was completely blocked by mines, and that it would be much quicker to clear the approaches to the Kalma Peninsula where we eventually landed ... 1stMarDiv dispatch [1450 24 Oct] cancelled both 1stMarDiv OpnOs 16 and 17 and provided for an administrative landing on the Kalma Peninsula as directed by CTF 90.” Gen O. P. Smith ltr to authors, 3 Feb 56. Hereafter, unless otherwise stated, letters may be assumed to be to the authors.
Two Weeks of Mine Sweeping
Mine sweeping for the Wonsan landing commenced on 8 October, when Task Group 95.6, commanded by Captain Spofford, began assembling for the mission of clearing a path ahead of the 250-ship armada bringing the 1st Marine Division and other units of X Corps. It had been known for a month that the waters of the east coast were dangerous for navigation. The first mine was discovered off Chinnampo on the west coast on 7 September, and four days later Admiral Joy ordered the United Nations Blocking and Escort Force to stay on the safe side of the 100-fathom line along the east coast. But it was not until 26 and 28 September that more definite information was acquired the hard way when the U. S. destroyer Brush and the ROK mine sweeper YMS 905 were damaged by east coast mines.[68]
[68] CinCPacFlt Interim Evaluation Report No. 1, VI, 1090.
On the 28th ComNavFE issued his OpnO 17-50 covering operations of mine sweepers in Korean waters. The herculean task awaiting the 12 available American vessels of this type may be judged by the fact that more than a hundred had been employed off Okinawa in World War II.
Although the exact date remained unknown, it was a safe assumption that North Korean mining activities, beginning in late July or early August, were speeded by the Inchon landing, which aroused the enemy to the peril of further amphibious operations. Russian instructors had trained Korean Reds at Wonsan and Chinnampo in the employment of Soviet-manufactured mines. Sampans, junks, and wooden coastal barges were used to sow a field of about 2000 in the harbor and approaches to Wonsan.[69]
[69] Ibid., VI, 1088–1089; Smith, Notes, 404; Karig, Korea, 301. See also ADVATIS Rpt 1225 in EUSAK WD, 24 Oct 50.
Captain Spofford’s TG 95.6 commenced its sweep off Wonsan on 10 October after a sortie from Sasebo. Unfortunately, the three large fleet sweepers, Pledge, Pirate, and Incredible, were not well adapted to the shallow sweeping necessary at Wonsan. More dependence could be placed in the seven small wooden-hulled U. S. motor mine sweepers Redhead, Mocking Bird, Osprey, Chatterer, Merganser, Kite, and Partridge, which were rugged even though low-powered. Spofford’s two big high-speed sweepers, Doyle and Endicott, had their limitations for this type of operation; and the nine Japanese and three ROK sweepers lacked some of the essential gear.[70]