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.
|Operation End Sweep|
|Part of the Vietnam War|
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.
|Planned by||U.S. Navy Mine Warfare Force|
|Objective||Clear mines from North Vietnamese waters|
|Date||6 February – 27 July 1973|
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.
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.
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.
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.
Ten ocean minesweepers (MSOs) were assigned to Task Force 78 to sweep deep-water approaches to North Vietnamese ports and inland waterways and to serve as helicopter control vessels. In addition, the tank landing ship USS Washtenaw County (LST-1166) was modified in Japan between November 1972 and February 1973 to serve in End Sweep as a "special device minesweeper," redesignated MSS-2. As such, she was intended to be used for check sweeps through waters which presumably were clear of active mines to ensure that passage indeed was safe. She was pumped full of polyurethane foam so that she would not sink if she struck a mine, was equipped with padding to protect her all-volunteer skeleton crew, and was modified so that her entire crew of six could remain topside during her minesweeping runs, ensuring that they would be blown overboard if she struck a mine rather than injured or killed by slamming into the overhead anywhere below decks.
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 HMH-463 and 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).
Task Force 78 was activated as a unit of the Seventh Fleet on 24 November 1972, while peace talks still were underway in Paris, and the ships and helicopter units making it up secretly gathered in the Philippines. The talks broke down in December 1972, however, so the task force awaited further developments into January 1973 while its helicopter crews practiced towing their minesweeping equipment in Subic Bay.
On 28 January 1973 – the day after the peace accords were signed – Task Force 78 departed the Philippines for Haiphong. McCauley met in Haiphong with his North Vietnamese opposite, Colonel Hoang Huu Thai, on 5 February 1973 to coordinate North Vietnamese actions with those of Task Force 78.
Minesweeping began on 6 February 1973, when the ocean minesweepers USS Engage (MSO-433), USS Force (MSO-445), USS Fortify (MSO-446), and USS Impervious (MSO-449) swept coastal waters near Haiphong, protected by the guided-missile frigate USS Worden (DLG-18) and destroyer USS Epperson (DD-719). On 27 February 1973, the amphibious assault ships USS Tripoli (LPH-10), USS New Orleans (LPH-11), and USS Inchon (LPH-12) and the amphibious transport docks USS Dubuque (LPD-8), USS Vancouver (LPD-2), USS Ogden (LPD-5), and USS Cleveland (LPD-7) joined the task force, carrying the 31 CH-53 Sea Stallion helicopters of HM-12, HMM-165, and HMH-463. The helicopters swept the main shipping channel to Haiphong the same day. The next day, however, President Nixon ordered a suspension of End Sweep in response to North Vietnamese delays in releasing prisoners-of-war.
End Sweep resumed on 6 March 1973. On 9 March 1973, a mine exploded – the only one to explode during End Sweep – as a minesweeping helicopter passed it and the explosion was captured on film by the helicopter's Swept Mine Locator. On 17 March 1973, Task Force 78 helicopters swept the ports of Hon Gai and Cam Pha. Elsewhere in North Vietnam, U.S. Navy technical personnel prepared 50 North Vietnamese sailors to conduct their own minesweeping operations and American C-130 Hercules transport aircraft, and helicopters from HMM-165 delivered minesweeping gear to the North Vietnamese at Cat Bi Airfield outside Haiphong.
Washtenaw County arrived at Haiphong from the Philippines on 6 April 1973, and made her first six check runs there on 14 April 1973, the first American ship to enter Haiphong harbor in over a decade. She had made only two out of a planned six runs the following day when further runs were suspended because the United States believed that the North Vietnamese government was not fulfilling its obligations under the Paris Peace Accords. Washington ordered a suspension of all minesweeping operations and, on 17 April 1973, Task Force 78 returned to Subic Bay for upkeep.
On 13 June 1973, the United States and North Vietnam signed a joint communiqué in Paris which, among other things, required that the United States resume minesweeping no later than 20 June and complete all minesweeping no later than 13 July. With all mines by now past their latest possible sterilization date, End Sweep resumed on 18 June 1973. On 20 June, Task Force 78 completed its check sweeps of Haiphong, and soon had also cleared Hon Gai and Cam Pha. Next, the task force concentrated on the coastal areas off Vinh. The final minesweeping operations took place on 5 July 1973 and the next day, Rear Admiral McCauley informed the North Vietnamese that the United States had concluded its mine countermeasures operations in North Vietnamese waters.
Operation End Sweep ended officially on 27 July 1973, and Task Force 78 withdrew from North Vietnamese waters the following day.
In addition to Engage, Force, Fortify, and Impervious, the ocean minesweepers USS Enhance (MSO-437), USS Illusive (MSO-448), USS Inflict (MSO-456), USS Leader (MSO-490), USS Conquest (MSO-488), and USS Esteem (MSO-438) took part in some part of End Sweep; six of the ten ocean minesweepers conducted actual sweeping operations, as did Washtenaw County in her special role. Nine amphibious warfare ships, six fleet tugs, three salvage ships, and 19 destroyer-type ships also operated in Task Force 78 during at least a portion of the six months of End Sweep.
Two helicopters were lost, and Enhance suffered fire damage during the operation. The overall cost of the operation, including repairs to Enhance, was $20,394,000 more than the cost expected for normal operations of the units involved. The six ocean minesweepers that had conducted actual minesweeping operations spent 439 hours involved in them.
Although End Sweep was a great success in the eyes of the American leadership and general public, U.S. Navy mine warfare analysts were less sanguine about what the operation had demonstrated. It was unusual in the U.S. Navy for a minesweeping operation to enjoy the political visibility and priority that End Sweep did, allowing the operation to make use of an amount and quality of U.S. Navy and Marine Corps staff, operational, and scientific resources not generally available to minesweeping, and analysts cautioned that such circumstances could not be counted on in future mine clearance campaigns. Moreover, the operation had been made relatively easy by the U.S. Navy's knowledge of the types and locations of the mines that had been laid, the selection of only magnetic mines during the minelaying campaign, and the planned self-sterilization of so many mines before sweeping began.
The American public and many U.S. Navy personnel came away from End Sweep with the impression that helicopters had replaced surface ships in the minesweeping role due to their effectiveness and far greater mobility. Here, too, Navy mine warfare analysts differed with the popular impression. While helicopters swept three to six times faster than surface minesweepers, they also proved to be very demanding in terms of logistical support and manpower, and often were down for repair due to the high stress of minesweeping on the helicopters. Navy mine warfare analysts concluded that a balanced force of surface minesweepers and helicopters supported by a significant number of support ships would be required in future mine clearance operations.
Cat Bi International Airport (IATA: HPH, ICAO: VVCI) (Vietnamese: Cảng hàng không quốc tế Cát Bi a.k.a. Vietnamese: Sân bay Quốc tế Cát Bi) is an international airport located in Hai Phong, Vietnam.HMH-463
Marine Heavy Helicopter Squadron 463 (HMH-463) is a United States Marine Corps helicopter squadron consisting of CH-53E Super Stallion transport helicopters. The squadron, also known as "Pegasus", is based at Marine Corps Air Station Kaneohe Bay, Hawaii and falls under the command of Marine Aircraft Group 24 (MAG-24) and the 1st Marine Aircraft Wing (1st MAW)Marine Aircraft Group 36
Marine Aircraft Group 36 (MAG-36) is an active air group of the United States Marine Corps, tasked with providing assault support aircraft. It is currently part of the 1st Marine Aircraft Wing (1st MAW), itself an integral part of the III Marine Expeditionary Force, and based at Marine Corps Air Station Futenma in Okinawa, Japan.Operation Pocket Money
Operation Pocket Money was the title of a U.S. Navy Task Force 77 aerial mining campaign conducted against the Democratic Republic of Vietnam (North Vietnam) from 9 May 1972 (Vietnamese time), during the Vietnam War. Its purpose was to halt or slow the transportation of supplies and materials for the Nguyen Hue Offensive (known in the West as the Easter Offensive), an invasion of the Republic of Vietnam (South Vietnam), by forces of the People's Army of Vietnam (PAVN), that had been launched on 30 March. Pocket Money was the first use of naval mines against North Vietnam.Third VA-95 (U.S. Navy)
The third VA-95 established April 1, 1972 and reclaiming the original "Green Lizards" name, the first VA-95 being established in 1943, as an Attack Squadron of the U.S. Navy. The second squadron was established on 1 April 1950, renamed the "Skyknights",. The unit returned to the name "Green Lizards" and was disestablished on 31 October 1995.USS Engage (MSO-433)
USS Engage (MSO-433), an Aggressive-class minesweeper, was the second ship of the United States Navy to be named Engage.
The second Engage (AM-433/MSO-433) was launched 18 June 1953 by Colberg Boat Works, Stockton, California; sponsored by Mrs. R. B. Richmond; and commissioned 29 June 1954, Lieutenant S. J. Martin in command. She was reclassified MSO-433, 7 February 1955. Originally intended to be USS Elusive it was changed to Engage to avoid potential phonetic conflict with USS Illusive (MSO-448).
From her home port at Long Beach, where she first arrived 21 July 1954, Engage operated in mine warfare and general training along the west coast, preparing for her deployments to the Far East in 1955-56, 1958, and 1960. During these, she trained with minecraft of the navies of the Republics of China and the Philippines, and the Royal Thailand navy, since an important duty for minecraft serving in the Far East is to improve the readiness of friendly navies to operate in mutual defense.
Engage participated in Operation Market Time (11 March 1965 to December 1972) which was created by joining the US Navy and the South Vietnamese Navy in an effort to stop the flow of supplies from North Vietnam into the south by sea. According to Navy reports, Operation Market Time was very successful, but received little credit. Eventually all the supply routes at sea became non-existent, which forced the North Vietnamese to use the Ho Chi Minh Trail.
Engage also participated in Operation End Sweep which began in January 1973. The last provision of the Vietnam war cease-fire agreement that directly related to the Navy entailed removal of the U.S. sea mines laid along the North Vietnamese coast and the Mark 36 Destructors dropped into inland waterways. On 28 January, following months of extensive preparation and training, the Seventh Fleet's Mine Countermeasures Force (Task Force 78), led by Rear Admiral Brian McCauley, sailed from Subic Bay and shaped course for a staging area off Haiphong. On 6 February, one day after Commander Task Force 78 met in the city to coordinate actions with his North Vietnamese opposite, Colonel Hoang Huu Thai, Operation End Sweep got underway. A total of 10 ocean minesweepers, 9 amphibious ships, 6 fleet tugs, 3 salvage ships, and 19 destroyer types served with Task Force 78 during the six months of Operation End Sweep.
Engage was decommissioned 30 December 1991 in Mayport, Florida. After decommissioning, Engage (ex MSO-433) remained in the Philadelphia inactive ships facility until delivered to Baltimore Marine. She was scrapped 17 May 2002.USS Enhance (AM-437)
USS Enhance (AM-437/MSO-437) was an Aggressive-class minesweeper acquired by the U.S. Navy for the task of removing mines that had been placed in the water to prevent the safe passage of ships.
Enhance was launched 11 October 1952 by Martinolich Shipbuilding Co., San Diego, California; sponsored by Mrs. A. C. Martinolich; reclassified MSO-437, 7 February 1955; and commissioned 16 April 1955, Lieutenant R. P. Green in command.USS Fortify (AM-446)
USS Fortify (AM-446/MSO-446) was an Agile-class minesweeper acquired by the U.S. Navy for the task of removing Contact, Magnetic, and Acoustic mines that had been placed in the water to prevent the safe passage of ships.
Fortify was launched 14 February 1953 by Seattle Shipbuilding and Drydocking Co., Seattle, Washington; sponsored by Mrs. Donald Scobie; and commissioned 16 July 1954, Lieutenant R. Juarez in command.USS Illusive (AM-448)
USS Illusive (AM-448/MSO-448) was an Agile-class minesweeper acquired by the U.S. Navy for the task of removing mines that had been placed in the water to prevent the safe passage of ships.
Illusive (AM-448) was launched by Martinolich Ship building Co., San Diego, California, 12 July 1952; sponsored by Mrs. Vito Marino; and commissioned 14 November 1953, Lt. Comdr. J. E. Ruzic in command.USS Inchon
USS Inchon (LPH/MCS-12) was an Iwo Jima-class amphibious assault ship of the United States Navy in service from 1970 to 2002. Following a major fire she was laid up and sunk as a target in 2004.USS New Orleans (LPH-11)
USS New Orleans (LPH-11) was an Iwo Jima-class amphibious assault ship in the United States Navy. She was the third Navy ship to be so named, and is the first named for the Battle of New Orleans, which was the last major battle of the War of 1812.
New Orleans was laid down on 1 March 1966 at the Philadelphia Naval Shipyard in Philadelphia, Pennsylvania. She was launched on 3 February 1968 and sponsored by Mrs. Arthur A. De la Houssaye. She was commissioned on 16 November 1968 with Captain G.M. Even in command.USS Ogden (LPD-5)
USS Ogden (LPD-5), an Austin-class amphibious transport dock, was the second ship of the United States Navy to be named for Ogden, Utah.
Ogden was laid down on 4 February 1963 by the New York Naval Shipyard. She was launched on 27 June 1964 sponsored by Mrs. Laurence J. Burton, and commissioned at New York City on 19 June 1965 with Captain Floyd M. Symons in command.USS Reasoner
USS Reasoner (FF-1063) was a Knox-class frigate of the United States Navy, named in honor of 1st Lt. Frank S. Reasoner, awarded the Medal of Honor posthumously in the Vietnam War.USS Westchester County (LST-1167)
USS Westchester County (LST-1167) was a Terrebonne Parish-class tank landing ship built for the United States Navy at the tail end of the Korean War. Named for Westchester County, New York, she was the only U.S. Naval vessel to bear the name. The ship served in the Vietnam War and was damaged by limpet mines set by Viet Cong frogmen. It was repaired and later sold to the Turkish Navy and finally sunk as a target in 2014.United States Seventh Fleet
The Seventh Fleet is a numbered fleet (a military formation) of the United States Navy. It is headquartered at U.S. Fleet Activities Yokosuka, in Yokosuka, Kanagawa Prefecture, Japan. It is part of the United States Pacific Fleet. At present, it is the largest of the forward-deployed U.S. fleets, with 60 to 70 ships, 300 aircraft and 40,000 Navy and Marine Corps personnel. Its principal responsibilities are to provide joint command in natural disaster or military operations and operational command of all naval forces in the region.VA-164 (U.S. Navy)
VA-164, nicknamed the Ghostriders, was an Attack Squadron of the U.S. Navy. It was established on 1 September 1960 and disestablished on 12 December 1975.VFA-147
Strike Fighter Squadron 147 (VFA-147), also known as the "Argonauts", is a United States Navy strike fighter squadron based at Naval Air Station Lemoore, California (USA). VFA-147 was established on 1 February 1967 and flies the F-35C Lightning II.
Easter Offensive (1972)
Post-Paris Peace Accords (1973–1974)