Fort Buchanan , Puerto Rico United States Army Garrison Fort Buchanan , Puerto Rico is the U . S . Army ’ s only active military installation in Puerto Rico . Located in the Metropolitan area of San Juan . Its mission is “ to provide Soldiers , Civilians and their Families with a quality of life commensurate with the quality of their service . ” Its vision statement “ Home Away From Home ” is to be the most desired Military Community in which to live , work and play . History . On November 19 , 1493 , Christopher Columbus discovered Puerto Rico during his second voyage to the New World . For four centuries , Puerto Rico was part of the Spanish Empire . There is a link between the history of Fort Buchanan and the history of the U . S . Army in Puerto Rico that dates back to the 19th century during the Spanish – American War . On July 25 , 1898 , U . S . forces landed in Guánica . On October 18 , 1898 the last Spanish unit left the island and the Department of Porto Rico was established . Upon the signing of the Treaty of Paris on December 10 , 1898 , Spain ceded Puerto Rico to the United States and the island became an unincorporated territory of the U . S . The Puerto Rico Regiment . On July 1 , 1899 , “ The Puerto Rico Regiment of Infantry , United States Army ” was created . On July 1 , 1901 Lieutenant Colonel James Anderson Buchanan commanded the regiment . He was later promoted to Colonel on July 21 , 1902 and to Brigadier General in 1905 . Buchanan served in Puerto Rico from 1898 to 1903 . The military installation , Fort Buchanan , was named after Brigadier General James A . Buchanan , the first commander of the Puerto Rico Regiment . Camp Buchanan . The Puerto Rico Regiment approved by Congress on May 27 , 1908 was officially designated as the 65th Infantry Regiment in 1920 , after defending the Canal Zone during World War I . A tract of 300 acres approximately six miles on the south shore of San Juan Bay was acquired to provide the regiment with a training area . The site was established in 1923 as Camp Buchanan . It served as a target range and maneuver area for Army and National Guard troops from 1923 to 1939 . Fort Buchanan . In May 1940 the location was designated as Fort Buchanan and expanded initially to 1 , 514 and later to 4 , 500 acres . During World War II , Fort Buchanan housed a depot supplying the Army Antilles Department . It also processed local troops through its replacement center . The industrial complex included pier facilities , ammunition storage areas and an extensive railroad network connecting the military installation to the bay . Puerto Rican soldiers were deployed for World War II and the Korean War from the train station located where the Golf Club is presently located , to the rail - connected Army terminal by the San Juan Bay . At the time , Fort Buchanan served as a citizens training camp and soldier processing station . After WW II the post was gradually reduced to its current 746 acres . Fort Buchanan remained a command depot with post facilities , a personnel center , and a special training center until closure as an Army post in 1966 . On December 31 , 1966 , with the deactivation of the Antilles Command , Fort Buchanan came under the U . S . Navy control . On December 7 , 1971 the Army took back Fort Buchanan under the control of Third U . S . Army . On July 1 , 1973 Fort Buchanan came under direct control of Forces Command ( FORSCOM ) . Following the Department of Defense Unified Command Plan , Fort Buchanan came under control of U . S . Southern Command ( SOUTHCOM ) , and on August 13 , 1999 became the home of U . S . Army South ( USARSO ) , which subsequently departed in 2003 . On October 1 , 2002 Fort Buchanan became part of the Southeast Regional Office of the Installation Management Agency ( IMA ) . On October 1 , 2003 , Fort Buchanan became an IMA Reserve installation . Later , on October 1 , 2006 Fort Buchanan became a Garrison under Installation Management Command , Southeast Region ( IMCOM - SE ) . On October 1 , 2008 the Commanding General of the 81st Regional Readiness Command became Fort Buchanan ’ s Senior Mission Commander under the U . S . Army Reserve Command . Based on the December 2008 Unified Command Plan , Fort Buchanan currently falls under the U . S . Northern Command ( USNORTHCOM ) area of operations , under the direct control of the United States Army Installation Management Command , Atlantic Region ( IMCOM - Atlantic ) . Today . USAG Fort Buchanan consists of 746 . 16 acres ( including Las Colinas , Coconut Grove and Coqui Gardens family housing ) with a real estate value estimated at $ 560 million . Fort Buchanan serves a population of approximately 130 , 000 combined between military personnel and their dependents , retirees , veterans , civilians , in Puerto Rico , Virgin Islands and Latin America . Fort Buchanan is host to a number of tenant activities , such as : the 1st Mission Support Command ( the U . S . Army Reserve major tenant unit ) , and other branches of the Reserve Component such as the U . S . Navy Reserve and the U . S . Marine Corps Reserve are tenants at Fort Buchanan . The Puerto Rico National Guard also has presence at Fort Buchanan . The Reserve Officer Training Corps ( ROTC ) held leadership labs and other activities at Fort Buchanan . The Army and Air Force Exchange Service ( AAFES ) , Defense Commissary Agency ( DECA ) , Rodriguez Army Health Clinic ( RAHC ) , Veterinary Treatment Facility , Defense Military Pay Office ( DMPO ) , Defense Contracting Audit Agency , TRICARE , Community Based Warriors in Transition Unit ( CBWTU ) , Civilian Personnel Advisory Center ( CPAC ) are some of the DoD service agencies at the base . Fort Buchanan also hosts a number of non - DoD organizations that provide valuable services to Soldiers , their dependants and community members , such as : Pentagon Federal Credit Union , Banco Popular de Puerto Rico , U . S . Postal Service and AAFES Concessionaires . Fort Buchanan also provides support to United States Department of Homeland Security agencies such as the U . S . Customs and Border Protection . As directed by the Chief of the Army Reserve , Fort Buchanan ' s island - wide support mission consists of providing real property management and base operations support for all Army Reserve assets in Puerto Rico and the U . S . Virgin Islands . Also , on a reimbursable basis , when requested , the garrison provides support to the Puerto Rico National Guard and other reserve components of other services . Fort Buchanan supports readiness and mission execution , providing quality services and facilities , optimizing resources , sustaining the environment and enhancing the well - being of the community . It conducts its mission sustained by seven directorates – Human Resources ; Family , Morale , Welfare and Recreation ( FMWR ) , Training , Mobilization and Security ; Emergency Services , Logistics , Public Works and Information Management ; seven support offices – Legal , Public Affairs , Religious Support , Equal Employment Opportunity , Safety , Internal Review and Contracting ; and three management and control offices – Resource Management ; Plans , Analysis and Integration ; and the Administrative Office . Among the factors that make U . S . Army Garrison Fort Buchanan unique are : its key and strategic location providing fast and cost - effective support to missions in the Caribbean , Central and South America area of responsibility ; its Hispanic cultural ties with Latin America ; and its significant role as host of “ joint ” sister services ’ from the Reserve Component of the United States Armed forces represented in Puerto Rico . General information . The base contains : Adjacent to Fort Buchanan : Armed Forces Reserve Center . An Armed Forces Reserve Center ( AFRC ) is under construction at Fort Buchanan to accommodate the U . S . Army Reserve will locate the Headquarters and Headquarters Detachment ( HHD ) of the 339th Battalion , ( the 393rd ) and a Retention Office . The Puerto Rico Army National Guard will locate the Recruiting and Retention Division ( R & R Div ) , the 480th MP Company , and Medical Section Cell C59 . The United States Marine Corps Reserve will locate the 3rd Longshoreman Platoon , the 4th Landing Support Battalion , and the 4th Marine Logistics Group will also move into this new facility . The Fort Buchanan Armed Forces Reserve Center will serve about 400 personnel on a rotating basis , with a maximum of 250 members per weekend . Puerto Rico National Guard Readiness Center . The Puerto Rico National Guard has bagan the construction of a $ 33 . 5 million Readiness Center at Fort Buchanan . The Puerto Rico National Guard Readiness Center at Fort Buchanan will include a Metal Storage Building / Maintenance Training Bay , Simulation Center / Physical Training , Emergency Generator and Tank , Vehicle Wash Platform and a Helipad .