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| Landing Ship, Medium | |
|---|---|
| Name | Landing Ship, Medium |
| In service | 1943–1950s |
| Type | Amphibious warfare ship |
| Displacement | ~4,080 tons full load |
| Length | 203 ft (62 m) |
| Beam | 34 ft (10 m) |
| Draft | 8 ft 3 in (2.5 m) light |
| Propulsion | Diesel engines, twin screws |
| Speed | 11–12 kn |
| Complement | 110–160 |
| Armament | Varied; 40 mm and 20 mm AA |
Landing Ship, Medium
Landing Ship, Medium served as a class of amphibious transport-cargo vessels employed principally by the United States Navy and allied navies during World War II and the early Cold War. Designed to carry vehicles, cargo, and embarked troops directly onto unimproved beaches, the class operated in multiple theaters including the Pacific Theater of Operations, the Mediterranean Theatre, and Southeast Asia, supporting operations linked to major campaigns such as Guadalcanal, Normandy landings, and the Philippine Campaign (1944–1945). Influenced by experiences in interwar amphibious experimentation and by doctrines advanced at institutions like the United States Marine Corps School and the Amphibious Training Center, the design balanced cargo capacity, beaching capability, and simplicity for mass production.
Design work on the Landing Ship, Medium arose from initiatives by the Office of the Chief of Naval Operations, the United States Maritime Commission, and amphibious doctrine advocates including personnel associated with the United States Navy Bureau of Ships and the Commander, Amphibious Forces Pacific Fleet. Influences included earlier prototypes such as the Landing Craft Tank and concepts tested by Experimental Landing Group exercises near Camp Pendleton (California), the Naval Proving Ground (Dahlgren), and the Cavite Navy Yard. Emphasis was placed on welded hull construction, diesel propulsion drawn from commercial designs promoted by the Kaiser Shipyards and the Sun Shipbuilding & Drydock Company, and a flat-bottom hull to permit deliberate beaching and retracting using cargo weight and ballast. Designers consulted plans held by the United States Army Transportation Corps and coordinated with Lend-Lease considerations affecting allied procurement by the Royal Navy, Royal Australian Navy, and Royal Canadian Navy.
Typical specifications reflected a compromise between cargo volume and shallow draft. Standard displacement approached 4,000 tons full load; length overall measured about 203 feet; beam near 34 feet; and light draft approximated 8 feet. Propulsion systems employed twin diesel engines driving two shafts, producing speeds around 11–12 knots adequate for convoy operations under the direction of Commander-in-Chief, United States Fleet routing. Crew complements varied, often between 110 and 160 enlisted and officers drawn from United States Naval Reserve and active components. Armament arrays included combinations of 40 mm Bofors and 20 mm Oerlikon anti-aircraft guns, supplemented on some units by 3"/50 caliber gun mounts for limited surface fire. Cargo capacity accommodated several medium tanks such as the M4 Sherman and dozens of vehicles, with bow ramp arrangements modeled on Landing Ship, Tank features and cargo handling equipment compatible with Sea Transport Service standards.
Landing Ship, Medium units entered service in 1943 and participated in major amphibious operations across multiple theaters. In the Solomon Islands campaign and Gilbert and Marshall Islands campaign, LSMs worked alongside Destroyer escorts, Attack Transport (APA) vessels, and Landing Craft, Infantry to deliver armor and supplies to contested beaches. During the Invasion of Normandy planning and follow-through logistics, analogous small amphibians and transferred LSMs supported cross-Channel sustainment under escort by units of the Western Task Force and Royal Navy Home Fleet. In the Philippine liberation, LSMs performed intra-archipelago lifts coordinated with Seventh Fleet amphibious forces and the Joint Chiefs of Staff directives. Crews faced threats from Imperial Japanese Army Air Service, German Luftwaffe remnants, coastal batteries, and minefields charted by Office of Naval Intelligence assessments. Postwar, some LSMs were retained for occupation duties and resupply missions during early Korean War mobilization.
The LSM hull proved adaptable to numerous conversions: rocket-equipped LSM(R) variants carried barrage rockets for pre-landing suppression used in operations influenced by studies at Naval Amphibious Base Coronado; some were converted to ambulance ships serving Hospital Ship roles in coordination with the Bureau of Medicine and Surgery; others became hydrographic survey vessels under the Hydrographic Office; and several were transferred and modified for service with the United States Coast Guard and allied navies including the French Navy, Royal Australian Navy, and Brazilian Navy. Experimental conversions tested additions such as improved radar suites from manufacturers associated with Radiomarine Corporation and electronic warfare fittings inspired by lessons from the Battle of Leyte Gulf.
Mass construction relied on a distributed industrial base spearheaded by yards such as Brown Shipbuilding, Dravo Corporation, Eastern Shipbuilding, and smaller firms contracted by the United States Maritime Commission. Prefabrication techniques honed in the Kaiser Shipyards and workforce mobilization efforts under National War Labor Board supervision accelerated delivery schedules. Shipyard employment involved coordination with the War Production Board and material supply from firms like Bethlehem Steel for plate and General Motors Diesel Division for engines. LSMs benefited from wartime standardization programs administered by the American Bureau of Shipping and design tweaks were issued by the Bureau of Ships as operational feedback arrived from theaters.
After World War II, many LSMs were decommissioned, placed in National Defense Reserve Fleet anchorages, sold to foreign navies, or repurposed into civilian use by commercial operators registered with the United States Coast Guard and the Federal Maritime Commission. A number saw renewed service during the Korean War under Military Sea Transportation Service auspices; others were scrapped during the 1950s and 1960s amid changing amphibious doctrines shaped by the NATO alliance and technological advances exemplified by the Landing Platform Dock. Several preserved examples entered museum collections alongside artifacts displayed at sites such as the National Museum of the United States Navy.
Notable LSMs include units that earned battle stars during key campaigns and those later transferred internationally. Examples recognized in archival holdings and veteran accounts are LSMs that served in the Marianas campaign, Okinawa campaign, and postwar transfers to navies of France, Mexico, and Taiwan (Republic of China) Navy. Crew memoirs and action reports filed with the Naval History and Heritage Command document distinguished service, rescue operations, and participation in major amphibious assaults.
Category:Amphibious warfare vessel classes Category:World War II naval ships of the United States