View source for Aggressive-class minesweeper

{{Short description|US built ocean minesweepers}}
{{Cleanup|reason=The lists in this article and [[Agile-class minesweeper]] should be disentangled.|date=August 2022}}
{{further|Agile-class minesweeper}}
{|{{Infobox ship begin}}
{{Infobox ship image
|Ship image=USS Constant (AM-427).jpg
|Ship image size=300px
|Ship caption=USS ''Constant'' (MSO-427) in 1988
}}
{{Infobox ship class overview
|Name=''Aggressive'' class
|Builders=
|Operators=*{{navy|United States}}
*{{navy|Republic of China}}
*{{navy|Belgium}}
*{{navy|Norway}}
*{{navy|Netherlands}}
*{{navy|Philippines|1936}}
|Class before=
|Class after=
|Subclasses= {{sclass|Onversaagd|minesweeper|4}}
|Cost=
|Built range=
|In service range=
|In commission range=1953–Present
|Total ships building=
|Total ships planned=
|Total ships completed=53
|Total ships cancelled=
|Total ships active=1
|Total ships laid up=
|Total ships lost=
|Total ships retired=52
|Total ships preserved=2
}}
{{Infobox ship characteristics
|Hide header=
|Header caption=
|Ship class=
|Ship type=[[Minesweeper]]
|Ship displacement= 853 tons (full load)
|Ship length= {{convert|172|ft|m|abbr=on|0}}
|Ship beam={{convert|35|ft|m|abbr=on|0}}
|Ship height=
|Ship draft={{convert|10|ft|m|abbr=on|0}}
|Ship depth=
|Ship power=
|Ship propulsion=*4 × aluminum block Waukesha diesels, {{convert|2,400|bhp|lk=in|abbr=on}}
*2 × shafts
*2 × controllable pitch propellers
|Ship speed= {{convert|14|kn|lk=in}}
|Ship range= 
|Ship endurance=
|Ship boats=
|Ship complement= 7 officers, 70 enlisted
|Ship sensors= AN/SQQ-14 mine hunting sonar
|Ship EW=
|Ship armament=*1 × twin [[Oerlikon 20 mm cannon|20 mm]] gun
*2 × [[M2 Browning|.50 cal (12.7 mm)]] twin machine guns
|Ship armor=
|Ship notes=
}}
|}

The '''''Aggressive''-class minesweepers''' are a class of US-built [[minesweeper]]s. They are designated as ''MSO'' (Mine Sweeper Ocean), distinguishing them from the smaller coastal MSCs and inshore MSIs. Besides the [[US Navy]], this class of vessels has also been used by the [[Belgian Navy]] and the [[Norwegian Navy]], among others.

==Background==
Minesweeping, or the disposal of [[naval mine]]s, by these vessels is performed in different ways:
*Sweeping proper, with an underwater cable cutting the mooring cables of moored mines. The mines then come to the surface and are destroyed by gunfire.
*Acoustic sweeping, with a towed device producing noise to trigger acoustic mines.
*Magnetic sweeping, with a towed device producing a magnetic field to trigger magnetic mines. To protect the minesweeper itself against magnetic mines, the hull and superstructure of the ship are made of wood. Other components are made of non-magnetic materials, and any magnetic materials are strictly controlled.

==Construction and disposition==
Of the 53 constructed for the United States Navy, 10 were built at [[Higgins Industries|Higgins Corp]]., [[New Orleans]], Louisiana, 9 at [[J.M. Martinac Shipbuilding Corp.]], [[Tacoma, Washington]], 8 at Wilmington Boat Works Inc., [[Wilmington, Los Angeles|Wilmington, California]], 6 at Luders Marine Construction Co. of [[Stamford, Connecticut]], 4 at Broward Marine Inc, [[Fort Lauderdale, Florida]], 4 at Martinolich Shipbuilding Co., [[San Diego]], California, 3 at Burger Boat Company, [[Manitowoc, Wisconsin]], 3 at [[Colberg Boat Works]], [[Stockton, California]], 2 at [[Fulton Shipyard]], [[Antioch, California]], 2 at [[Norfolk Naval Shipyard]] and 2 at Seattle Shipbuilding and Drydocking Co., [[Seattle]], [[Washington (state)|Washington]].

33 of the class were decommissioned before the mid-1970s. Four ex-USN ships were sold to the [[Republic of China Navy]] 1994 and re-classed as {{sclass|Yung Yang|minesweeper|1}}s. They were still in active service in 2012. {{USS|Implicit|MSO-455|6}} was decommissioned 30 September 1994 in Tacoma, Washington and was the last ''Aggressive''-class minesweeper in US Navy active service.

<gallery>
File:USS Conquest (MSO-488) mine detection sonar console.jpg|A crewman monitors a mine detection and classification sonar console aboard the ocean minesweeper USS ''Conquest'' 
File:USS Conquest (MSO-488) mine detection and classification console.jpg|A crewman monitors a mine detection and classification console aboard the ocean minesweeper USS ''Conquest''
File:Paravane aboard USS Engage (MSO-433).jpg|A [[Paravane (weapon)|paravane]] used for mine sweeping aboard USS ''Conquest'' 
File:USS Illusive (MSO-448) lowers an acoustical device during an exercise.jpg|USS ''Illusive'' lowers an acoustical device during an exercise.
File:USS Illusive (MSO-448) lowers an acoustical device for training 2.jpg|USS ''Illusive''  lowers a different acoustical device for training.
File:USS Illusive (MSO-448) deploys a mineweeping cable.jpg|USS ''Illusive'' deploys a mineweeping cable.
File:USS Constant (MSO-427) deploying the mag-tail.jpg|USS ''Constant'' deploying the "mag-tail", used to simulate the magnetic field of a vessel, are towed behind the ship to trigger magnetic mines.
File:Super Sea Rover aboard USS Conquest (MSO-488).jpg|A remote control mine-seeking system, Super Sea Rover, aboard USS ''Conquest''
File:USS Esteem (MSO-438) deploys a marker.jpg|USS ''Esteem'' deploys a marker, for marking mines or mine fields.
</gallery>
{{-}}

==Units==
{| class="wikitable"
|-
!Ship Name
!Hull no.
!Builder
!Commission–<br />Decommission
!Fate
!Link
|-
|{{USS|Aggressive|MSO-422|2}}<ref>{{Naval Vessel Register URL|id=MSO422|title=AGGRESSIVE (MSO 422)}}</ref> 
|422
|Luders Marine Construction Co. of [[Stamford, Connecticut]]
|1953–1971
|Sold for scrap 1980
|
|-
|{{USS|Avenge|MSO-423|2}} 
|423
|Luders Marine Construction Co. of [[Stamford, Connecticut]]
|1954-1970
|Destroyed by fire, sold for scrapping 1969||
|-
|{{USS|Bold|MSO-424|2}}<ref>{{Naval Vessel Register URL|id=MSO424|title=Naval Vessel Register}}</ref> ||424||[[Norfolk Naval Shipyard]]||1953-1971||Sold for scrap 1981||
|-
|{{USS|Bulwark|MSO-425|2}}<ref>{{Naval Vessel Register URL|id=MSO425|title=Naval Vessel Register}}</ref> 
|425
|[[Norfolk Naval Shipyard]]
|1953-1971
|Sold for scrap 1980
|
|-
|{{USS|Conflict|MSO-426|2}}<ref>{{Naval Vessel Register URL|id=MSO426|title=Naval Vessel Register}}</ref>
|426||[[Fulton Shipyard]], [[Antioch, California]]
|1954-1973
|Sold for scrap 1973
|
|-
|{{USS|Constant|MSO-427|2}} ||427||[[Fulton Shipyard]]., [[Antioch, California]]||1954-1992||Sold for scrap 2001||{{Naval Vessel Register URL|id=MSO427|title=Naval Vessel Register}}
|-
|colspan=6|428 - 431 were US ''Dash''-class minesweepers
|-
|{{USS|Dynamic|MSO-432|2}} ||432||[[Colberg Boat Works]]., [[Stockton, California]] ||1953-1971 ||Sold or loaned to Spain as ''Guadalete'' M41, 1971. ||{{Naval Vessel Register URL|id=MSO432|title=Naval Vessel Register}}
|-
|{{USS|Engage|MSO-433|2}} ||433||[[Colberg Boat Works]]., [[Stockton, California]] ||1953-1991 ||Scrapped 2002 ||{{Naval Vessel Register URL|id=MSO433|title=Naval Vessel Register}}
|-
|{{USS|Embattle|MSO-434|2}} ||434||[[Colberg Boat Works]]., [[Stockton, California]] ||1954-1972 ||Sold to be scrapped 1976, privately held until scrapped by USACE in 1993.||{{Naval Vessel Register URL|id=MSO434|title=Naval Vessel Register}}
|-
|{{USS|Endurance|MSO-435|2}} ||435||J. M. Martinac Shipbuilding Corp., [[Tacoma, Washington]] ||1954-1972 ||Sold for scrap 1973 ||{{Naval Vessel Register URL|id=MSO435|title=Naval Vessel Register}}
|-
|{{USS|Energy|MSO-436|2}} ||436||J. M. Martinac Shipbuilding Corp., [[Tacoma, Washington]] ||1954-1972 ||Loaned to Philippines 1972<br>Sold for scrap 1977 ||{{Naval Vessel Register URL|id=MSO436|title=Naval Vessel Register}}
|-
|{{USS|Enhance|MSO-437|2}} ||437||Martinolich Shipbuilding Co., [[San Diego|San Diego, California]] ||1955-1970<br>1971-1991 ||Sold for scrap 2000 ||{{Naval Vessel Register URL|id=MSO437|title=Naval Vessel Register}}
|-
|{{USS|Esteem|MSO-438|2}} ||438||Martinolich Shipbuilding Co., [[San Diego|San Diego, California]] ||1955-1970<br>1971-1991 ||Sold for scrap 2000 ||{{Naval Vessel Register URL|id=MSO438|title=Naval Vessel Register}}
|-
|{{USS|Excel|MSO-439|2}} ||439||[[Higgins Industries|Higgins Corp]]., [[New Orleans|New Orleans, Louisiana]] ||1955-1992 ||Sold for scrap 2000 ||{{Naval Vessel Register URL|id=MSO439|title=Naval Vessel Register}}
|-
|{{USS|Exploit|MSO-440|2}} ||440||[[Higgins Industries|Higgins Corp]]., [[New Orleans|New Orleans, Louisiana]] ||1954-1993 ||Sold for scrap 2002 ||{{Naval Vessel Register URL|id=MSO440|title=Naval Vessel Register}}
|-
|{{USS|Exultant|MSO-441|2}} ||441||[[Higgins Industries|Higgins Corp]]., [[New Orleans|New Orleans, Louisiana]] ||1954-1993 ||Sold for scrap 2002 ||{{Naval Vessel Register URL|id=MSO441|title=Naval Vessel Register}}
|-
|{{USS|Fearless|MSO-442|2}} ||442||[[Higgins Industries|Higgins Corp]]., [[New Orleans|New Orleans, Louisiana]] ||1954-1990 ||Sold for scrap 1992 ||{{Naval Vessel Register URL|id=MSO442|title=Naval Vessel Register}}
|-
|{{USS|Fidelity|MSO-443|2}} ||443||[[Higgins Industries|Higgins Corp]]., [[New Orleans|New Orleans, Louisiana]] ||1955-1989 ||Sold for scrap 1990 ||{{Naval Vessel Register URL|id=MSO443|title=Naval Vessel Register}}
|-
|{{USS|Firm|MSO-444|2}} ||444||J. M. Martinac Shipbuilding Corp., [[Tacoma, Washington]] ||1954-1972 ||Loaned to Philippines 1972<br>Scrapped 1977 ||{{Naval Vessel Register URL|id=MSO444|title=Naval Vessel Register}}
|-
|{{USS|Force|MSO-445|2}} ||445||J. M. Martinac Shipbuilding Corp., [[Tacoma, Washington]] || 1955-1973 ||Sunk after a fire ||{{Naval Vessel Register URL|id=MSO445|title=Naval Vessel Register}}
|-
|{{USS|Fortify|MSO-446|2}} ||446||Seattle Shipbuilding and Drydocking Co., [[Seattle]], [[Washington (state)|Washington]] ||1954-1992 ||Scrapped 2002 ||{{Naval Vessel Register URL|id=MSO446|title=Naval Vessel Register}}
|-
|{{USS|Guide|MSO-447|2}} ||447||Seattle Shipbuilding and Drydocking Co., [[Seattle]], [[Washington (state)|Washington]] ||1955-1972 ||Sold for scrap 1973 ||{{Naval Vessel Register URL|id=MSO447|title=Naval Vessel Register}}
|-
|{{USS|Illusive|MSO-448|2}} ||448||Martinolich Shipbuilding Co., [[San Diego|San Diego, California]] ||1953-1990 ||Sold for scrap 1993 ||{{Naval Vessel Register URL|id=MSO448|title=Naval Vessel Register}}
|-
|{{USS|Impervious|AM-449|2}} ||449||Martinolich Shipbuilding Co., [[San Diego|San Diego, California]] ||1954-1991 ||Scrapped 2002 ||{{Naval Vessel Register URL|id=MSO449|title=Naval Vessel Register}}
|-
|colspan=6|450 - 454 built at Bellingham Shipyards Co., [[Bellingham, Washington]] for France, not necessarily ''Aggressive''-class ships.
|-
|{{USS|Implicit|AM-455|2}} ||455||[[Wilmington Boat Works Inc]]., [[Wilmington, California]] ||1954-1994 ||Sold to Taiwan 1994 ||{{Naval Vessel Register URL|id=MSO455|title=Naval Vessel Register}}
|-
|{{USS|Inflict|AM-456|2}} ||456||[[Wilmington Boat Works Inc]]., [[Wilmington, California]] ||1954-1990 ||Sold for scrap 1992 ||{{Naval Vessel Register URL|id=MSO456|title=Naval Vessel Register}}
|-
|{{USS|Loyalty|AM-457|2}} ||457||[[Wilmington Boat Works Inc]]., [[Wilmington, California]] ||1954-1972 ||Sold for scrap 1973 ||{{Naval Vessel Register URL|id=MSO457|title=Naval Vessel Register}}
|-
|{{USS|Lucid|MSO-458|2}} ||458||[[Higgins Industries|Higgins Corp]]., [[New Orleans|New Orleans, Louisiana]] ||1955-1970 ||Sold for scrap 1976<br>Currently being restored by the [http://www.stocktonhistoricalmaritimemuseum.org/ Stockton Historical Maritime Museum] as a museum ship ||{{Naval Vessel Register URL|id=MSO458|title=Naval Vessel Register}}
|-
|{{USS|Nimble|AM-459|2}} ||459||[[Higgins Industries|Higgins Corp]]., [[New Orleans|New Orleans, Louisiana]] ||1955-1970 ||Sold for scrap 1981 ||{{Naval Vessel Register URL|id=MSO459|title=Naval Vessel Register}}
|-
|{{USS|Notable|MSO-460|2}} 
|460
|[[Higgins Industries|Higgins Corp]]., [[New Orleans|New Orleans, Louisiana]] 
|1955-1970 
|Sold for scrap 1971 
|{{Naval Vessel Register URL|id=MSO460|title=Naval Vessel Register}}
|-
|{{USS|Observer|MSO-461|2}} 
|461
|[[Higgins Industries|Higgins Corp]]., [[New Orleans|New Orleans, Louisiana]] 
|1955-1972 
|Sold for scrap 1979 
|{{Naval Vessel Register URL|id=MSO461|title=Naval Vessel Register}}
|-
|{{USS|Pinnacle|MSO-462|2}} ||462||[[Higgins Industries|Higgins Corp]]., [[New Orleans|New Orleans, Louisiana]] ||1955-1970 ||Sold for scrap 1978 ||{{Naval Vessel Register URL|id=MSO462|title=Naval Vessel Register}}
|-
|{{USS|Pivot|MSO-463|2}} ||463||[[Wilmington Boat Works Inc]]., [[Wilmington, California]] ||1954-1971 ||Initially loaned then sold to Spain as ''Guadalmedina'' M42, 1974. Decommissioned by Spain 2001.||{{Naval Vessel Register URL|id=MSO463|title=Naval Vessel Register}}
|-
|{{USS|Pluck|MSO-464|2}} ||464||[[Wilmington Boat Works Inc]]., [[Wilmington, California]] ||1954-1990 ||Sold for scrap 1992 ||{{Naval Vessel Register URL|id=MSO464|title=Naval Vessel Register}}
|-
|{{USS|Prestige|MSO-465|2}} ||465||[[Wilmington Boat Works Inc]]., [[Wilmington, California]] ||1954-1958 ||Grounded and sunk, 1958 in the [[Naruto Strait]] ||
|-
|{{USS|Prime|AM-466|2}} ||466||[[Wilmington Boat Works Inc]]., [[Wilmington, California]] ||1954-1970 ||Sold for scrap 1976 ||{{Naval Vessel Register URL|id=MSO466|title=Naval Vessel Register}}
|-
|{{USS|Reaper|MSO-467|2}} ||467||[[Wilmington Boat Works Inc]]., [[Wilmington, California]] ||1954-1972 ||Sold for scrap 1976 ||{{Naval Vessel Register URL|id=MSO467|title=Naval Vessel Register}}
|-
|{{USS|Rival|MSO-468|2}} ||468||Luders Marine Construction Co. of [[Stamford, Connecticut]] ||1954-1970 ||Sold for scrap 1971 ||{{Naval Vessel Register URL|id=MSO468|title=Naval Vessel Register}}
|-
|{{USS|Sagacity|MSO-469|2}} ||469||Luders Marine Construction Co. of [[Stamford, Connecticut]] ||1955-1970 ||Grounded at Charleston Harbor then sold for scrap 1970. ||
|-
|{{USS|Salute|AM-470|2}} ||470||Luders Marine Construction Co. of [[Stamford, Connecticut]] ||1955-1970 ||Sold for scrap 1971 ||{{Naval Vessel Register URL|id=MSO470|title=Naval Vessel Register}}
|-
|{{USS|Skill|MSO-471|2}} ||471||Luders Marine Construction Co. of [[Stamford, Connecticut]] ||1950-1970 ||Sold for scrap 1979, scrapped 1983. ||{{Naval Vessel Register URL|id=MSO471|title=Naval Vessel Register}}
|-
|{{USS|Valor|AM-472|2}} ||472||Burger Boat Company, [[Manitowoc, Wisconsin]] ||1954-1970 ||Sold for scrap 1971 ||{{Naval Vessel Register URL|id=MSO472|title=Naval Vessel Register}}
|-
|{{USS|Vigor|AM-473|2}} ||473||Burger Boat Company, [[Manitowoc, Wisconsin]] ||1954-1972 ||Sold to Spain as ''Guadiana'' M44, 1972. Scrapped by Spain after 1999. ||{{Naval Vessel Register URL|id=MSO473|title=Naval Vessel Register}}
|-
|{{USS|Vital|MSO-474|2}} ||474||Burger Boat Company, [[Manitowoc, Wisconsin]] ||1955-1972 ||Sold for scrap 1979 ||{{Naval Vessel Register URL|id=MSO474|title=Naval Vessel Register}}
|-
|colspan=6|475 - 487 built for France, Portugal, Spain, Belgium and the Netherlands, not necessarily ''Aggressive''-class ships.
|-
|{{USS|Conquest|AM-488|2}} 
|488
|J. M. Martinac Shipbuilding Corp., [[Tacoma, Washington]] 
|1955-1970<br>1971-1994 
|Sold to Taiwan 1994 and decommissioned in 2020. 
|{{Naval Vessel Register URL|id=MSO488|title=Naval Vessel Register}}
|-
|{{USS|Gallant|MSO-489|2}} 
|489||J. M. Martinac Shipbuilding Corp., [[Tacoma, Washington]] 
|1955-1994 
|Sold to Taiwan 1994 and decommissioned in 2013.
|{{Naval Vessel Register URL|id=MSO489|title=Naval Vessel Register}}
|-
|{{USS|Leader|MSO-490|2}} 
|490
|J. M. Martinac Shipbuilding Corp., [[Tacoma, Washington]] 
|1955-1970<br>1971-1991/92 
|Sold for scrap 1994 
|{{Naval Vessel Register URL|id=MSO490|title=Naval Vessel Register}}
|-
|{{USS|Persistent|MSO-491|2}} 
|491||J. M. Martinac Shipbuilding Corp., [[Tacoma, Washington]] 
|1956-1971 
|Initially loaned in 1971 then sold to Spain as ''Guadalquivir'' M43 
|{{Naval Vessel Register URL|id=MSO491|title=Naval Vessel Register}}
|-
|{{USS|Pledge|MSO-492|2}}<ref>{{Naval Vessel Register URL|id=MSO492|title=Naval Vessel Register}}</ref> 
|492
|J. M. Martinac Shipbuilding Corp., [[Tacoma, Washington]] 
|1956-1994 
|Sold to Taiwan 1994 and decommissioned 2021.
|{{Naval Vessel Register URL|id=MSO492|title=Naval Vessel Register}}
|-
|{{USS|Stalwart|MSO-493|2}} ||493||Broward Marine Inc, [[Fort Lauderdale, Florida]] ||1956-1966 ||Caught fire pier side at San Juan, Puerto Rico, sunk 1966. Later raised and sunk as an artificial reef. ||
|-
|{{USS|Sturdy|MSO-494|2}} ||494||Broward Marine Inc, [[Fort Lauderdale, Florida]] ||1957-1971 ||Sold for scrap 1978 ||{{Naval Vessel Register URL|id=MSO494|title=Naval Vessel Register}}
|-
|{{USS|Swerve|MSO-495|2}} ||495||Broward Marine Inc, [[Fort Lauderdale, Florida]] ||1957-1971 ||Sold for scrap 1978 ||{{Naval Vessel Register URL|id=MSO495|title=Naval Vessel Register}}
|-
|{{USS|Venture|MSO-496|2}} <ref>{{Naval Vessel Register URL|id=MSO496|title=Naval Vessel Register}}</ref>
|496
|Broward Marine Inc, [[Fort Lauderdale, Florida]]
|1958-1971 
|Sold for scrap 1978 
|
|-
|MSO-497
|497
|colspan=4 |Cancelled, never built
|}

==See also==
* [[HNLMS Onverschrokken (M886)]] - Dutch ''Aggressive''-class minesweeper

==References==
{{Reflist}}

==External links==
{{commons category|Agile-class minesweepers}}
*[http://www.fas.org/man/dod-101/sys/ship/mso-422.htm FAS - MSO-422 class]
*[http://www.globalsecurity.org/military/systems/ship/mso-422.htm GlobalSecurity - MSO-422 class]
*[http://www.museumschip-mercuur.nl ex MSO 483]

{{Aggressive class minesweeper}}

{{DEFAULTSORT:Aggressive Class Minesweeper}}
[[Category:Aggressive-class minesweepers| ]]
[[Category:Mine warfare vessel classes]]