Operation End Sweep
{{Short description|Part of the Vietnam War (1973)}}
{{Use dmy dates|date=December 2024}}
{{operational plan
| name = Operation End Sweep
| partof = the Vietnam War
| image = File:Mine explosion Operation End Sweep 9 March 1973.jpg
| caption = A naval mine explodes in Haiphong Harbor on 9 March 1973 during Operation End Sweep, photographed by the automatic mine locator camera aboard an American CH-53A Sea Stallion helicopter. It is believed to be the only explosion of a mine during End Sweep. The Mark 105 hydrofoil minesweeping sled the helicopter is towing is at right
| scope = Minesweeping
| planned =
| planned_by = U.S. Navy Mine Warfare Force
| objective = Clear mines from North Vietnamese waters
| executed = 6 February – 27 July 1973
| executed_by = *U.S. Navy
| outcome = Operational success
}}
{{Campaignbox Vietnam War}}
{{History of Hải Phòng}}
Operation End Sweep was a United States Navy and United States Marine Corps operation to remove naval mines from Haiphong harbor and other coastal and inland waterways in North Vietnam between February and July 1973. The operation fulfilled an American obligation under the Paris Peace Accord of January 1973, which ended direct American participation in the Vietnam War. It also was the first operational deployment of a U.S. Navy air mine countermeasures capability.Melia, pp. 99–101.
Background
The United States had largely disengaged from the Vietnam War when North Vietnam launched its Easter Offensive into South Vietnam in March 1972. In response, the United States Air Force and U.S. Navy launched Operation Linebacker, a major bombing offensive against North Vietnam. In addition, President of the United States Richard Nixon ordered the Commander-in-Chief, United States Pacific Fleet, Admiral Bernard A. Clarey, and the Commander-in-Chief, United States Seventh Fleet, Vice Admiral James L. Holloway, to begin the Operation Pocket Money mining campaign against Haiphong and other North Vietnamese ports. The mining campaign, by U.S. Navy and United States Marine Corps attack aircraft from American aircraft carriers, began on 8 May 1972, and over the next several months laid thousands of mines in North Vietnamese waters.Melia, p. 101.[https://web.archive.org/web/20031009211949/http://www.history.navy.mil/wars/vietnam/minenorviet.htm "U.S. Mining and Mine Clearance in North Vietnam" by Edward J. Marolda, Naval History and Heritage Command, United States Department of the Navy][http://102msos.8m.net/operationendsweep.html OPERATION END SWEEP 6 February 1973 – 27 July 1973 The removal of mines from North Vietnam{{'}}s coastal and inland waters]
Eventually, North Vietnam and the United States negotiated an end to the war and signed the Paris Peace Accords on 27 January 1973. A protocol to the agreement called for the United States to neutralize American mines in North Vietnam{{'}}s coastal and inland waterways.Melia, p. 109.
Preparations
Under the Hague Convention of 1907, the United States was required to eliminate the mine threat it had created after the end of hostilities. Accordingly, the U.S. Navy{{'}}s Mine Warfare Force (MINEWARFOR) began planning for removal of the mines as soon as Nixon ordered the mining campaign to begin. In order to ease post-war minesweeping, only mines that could be cleared by magnetic sweeps were used, and the vast majority of mines laid were programmed either to self-destruct or render themselves inert after a specified period of time. Of course, the U.S. Navy also knew generally where the mines had been laid, although the inherent inaccuracy of aerial minelaying meant that the precise location of each mine was not known.
Rear Admiral Brian McCauley became Commander, Mine Warfare Force, and Commander, Task Force 78, in September 1972. Task Force 78 was designated as Mine Countermeasures Force, U.S. Seventh Fleet, and was created for the upcoming minesweeping operation that would become known as End Sweep.
Minesweeping equipment and U.S. Navy personnel trained in minesweeping both were in short supply, so, in order to minimize the danger of mine explosions to American personnel and equipment, Task Force 78 planners devised an operational scheme in which minesweeping was limited to areas in which the mines already had rendered themselves inert. If all mines known to be in an area also were known to have passed their self-sterilization dates, Task Force 78 planned to conduct a check sweep of a few passes; if it was not clear that all mines in a given area had become inert, a more thorough clearance sweep was to be used.Melia, pp. 104–105.
In the United States, the Chief of Naval Materiel, Admiral Isaac C. Kidd, Jr., organized a Mine Warfare Program Office charged with controlling scientific and technical support to End Sweep. The program office ensured that resources were allocated to the operation that allowed the rapid development of shallow-water minesweeper gear and precision navigation and locating systems, the latter providing minesweeping forces with an improved capability to determine the configuration of a minefield and to adjust their daily operations accordingly.Melia, p. 105.
File:Sikorsky CH-53 lifts a magnetic mine countermeasure device from USS Inchon (LPH-12) at Naval Station Subic Bay, Philippines, circa in January 1973 (USN 1155763).jpg {{USS|Inchon|LPH-12}} lifts a Magnetic Orange Pipe (MOP) mine countermeasure device during training at Subic Bay in the Philippines.
The Navy's newly created air mine countermeasures capability resided entirely in the CH-53 Sea Stallion helicopters of Helicopter Mine Countermeasures Squadron 12 (HM-12), all of which were assigned to the operation. In addition, one detachment each from the Marine Corps{{'}}s Marine Heavy Helicopter Squadron 463 (HMH-463) and Marine Medium Helicopter Squadron 164 (HMM-164) provided a total of 24 more CH-53s. The helicopters practiced for the operation off Charleston, South Carolina, where it was discovered that the Marine Corps pilots{{'}} inexperience in towing the heavy Mark 105 hydrofoil minesweeping sleds posed a risk to the personnel and equipment involved, a particularly unacceptable risk because of the scarcity and expense of the sleds. As a result, a scientist devised a buoyant, magnetized pipe filled with styrofoam which any helicopter pilot could tow easily. Painted orange, the new device became known as the Magnetic Orange Pipe (MOP).Melia, p. 107.
