Brown - water navy Brown - water navy is a term that originated in the United States Navy , referring to the small gunboat s and patrol boat s used in rivers , along with some of the larger ships ( including converted WWII LCM s , LST s , etc . ) that supported them as " mother ships , " from which they operated . A broader meaning is any naval force that has the capacity to carry out military operation s in river or littoral environments . The term " brown - water " generally describes river environments carrying heavy sediment loads , such as from soil runoff or flooding . Since presence of " brown water " requires a soil source , whether riverine or coastal , the term has become associated with littoral navies . The term is used in contrast to the terms " green - water navy " and " blue - water navy " . At one time , it was common to refer to all non - blue - water navies as " brown - water navies " . Today blue - water navies are generally defined as being capable of sustained oversea deployment , preferably with aircraft carriers , while green - water navies are defined as those with frigates or better , operating in coastal and regional areas . Being a brown - water navy does not imply a lack of offensive capability , as many small littoral combat ship s are armed with powerful anti - ship missile s . History . After losing its blue - water fleet in the Battle of Copenhagen ( 1807 ) , the kingdom of Denmark - Norway quickly built a brown - water navy . The partial successes of the resulting Gunboat War were undone by land invasion . United States . American Civil War . The term " brown - water navy " originated in the American Civil War ( 1861 – 1865 ) . As a blueprint for the " strangulation " of the Confederate States of America , Winfield Scott ' s Anaconda plan called for a two - pronged approach by first blocking the South ' s harbors and then pushing along the Mississippi River , effectively cutting the Confederate territory in two while also robbing the South of its main artery of transport . The U . S . Navy was assigned the blockade of the seaports , while a new force of gunboat s and river ironclad s , together with regular army units , would take , or at least lay siege on , the Confederate forts and cities along the Mississippi . In the early days of the war , these boats were built and crewed by the U . S . Army , with the naval officers commanding them being the only direct connection to the U . S . Navy . By the autumn of 1862 , the boats and their mission were transferred to the Department of the Navy . Because of the river ' s murky brown water , the ships that participated in these Mississippi campaigns were quickly referred to as the " brown - water navy " , as opposed to the regular U . S . Navy ( which was henceforth referred to as the " deep - water " or " blue - water " navy ) . Gunboat Diplomacy . Save for an occasional river patrol boat , the river ironclad navy was all but abolished at the end of the Civil War . Yet the concept of a river defense force lived on in countries and regions where rivers enabled the US to project its military presence , allowing it to protect its foreign interests abroad . US river boats ( gunboats ) of the Asiatic Fleet operated in portions of Chinese rivers ( sometimes referred to as the " Asiatic Navy " ) during the 1920s , such as the gunboat , which was sunk in 1937 ( by Japanese aircraft , prior to WWII ) , and the , which was captured by the Japanese in December 1941 . The US Navy during that era was , under the terminology used then , protecting US foreign policy and her citizens abroad via " Gunboat diplomacy " . The China gunboat was lost in action March 1942 . Vietnam . On 18 December 1965 , for the first time since the American Civil War , the United States Navy formalized the new brown - water Navy in Vietnam . Its primary mission would be to interdict enemy re - supply , and any contraband which might contribute to the enemy ' s war effort . In the beginning , the brown - water navy patrolled the inland waterways , primarily with South Vietnamese river craft ( RAG — River Assault Groups ) which had been mostly inherited from the French during their war ; which in turn , had been received from the US , as military aid , during the French fight against the Viet Minh ( Communist - led Vietnamese alliance ) . As the new fiberglass PBR ( Patrol Boat , River ) , using water jet propulsion , became available , it became the main interdiction vessel for the inland waterways . For close coastal waters during the war , more seaworthy South Vietnamese Navy water craft were used , until replaced by newer Navy Swift Boat s ( PCF — Patrol Craft Fast , aluminum 50 footers ) and United States Coast Guard Point - class cutter s . By the late 1960s , the Swift Boat would commence operations alongside the PBR ' s in the inland waters , as well as maintaining operations along the coast line . The brown - water navy was a joint venture between the Navy and the Army , modeled after the earlier French Riverine and coastal patrols in the First Indochina War ( 1945 – 1954 ) . In the beginning this force consisted of mostly modified surplus US WWII Landing craft ( boats ) , such as the LCM s , LCVP s , LCI s , etc . The only entirely new riverine boat from the French Indochina War had been the French designed STCN ( an all - steel " V " hulled boat , approximately 40 feet in length , whose design had been influenced by the US LCVP ) . This particular craft influenced the design of the US Navy ' s only original riverine boat built for the Vietnam War ; the 50 - foot all - steel hull , aluminum super - structured ASPB ( Assault Support Patrol Boat , better known as the " Alpha Boat " ) . The " Alpha " boat was built by the Gunderson Company , in Oregon , USA , and was of reinforced construction , in order to survive exploding mines . As a consequence , the ASPB earned a reputation as the " mine - sweeper " of the riverine forces . Other riverine craft included , along with the aforementioned PBRs , PCFs , and ASPBs , were the Patrol Air Cushion Vehicle s ( PACVs ) , Coast Guard Point - class 82 - foot patrol boats , and the Monitors ( modified LCMs ) . Together these craft formed a Mobile Riverine Force , that utilized various supporting facilities , such as the Yard Repair Berthing and Messing s , advance bases , LSTs , helicopter and seawolf units . The brown - water navy was largely successful in its tactics to combat infiltration and weapons smuggling during its existence between 1965 and 1970 . The units were formalized in January 1967 with the 2nd Brigade , 9th Infantry Division arriving under the command of Major General William Fulton . Later that same year , in combination with US Navy Task Force 117 they formed the Mobile Riverine Force . In 1970 , for the last time since the Civil War , the Navy stood down the last of its brown - water navy units ; as they were turned over to the South Vietnamese and Cambodian Governments under the Vietnamization policy .