Fort Yuma Fort Yuma is a fort in California that is located in Imperial County , across the Colorado River from Yuma , Arizona . It was on the Butterfield Overland Mail route from 1858 until 1861 and was abandoned May 16 , 1883 , and transferred to the Department of the Interior . The Fort Yuma Indian School and the Saint Thomas Yuma Indian Mission now occupy the site . It is one of the " associated sites " listed as Yuma Crossing and Associated Sites on the National Register of Historic Places in the Yuma Crossing National Heritage Area . In addition , it is registered as California Historical Landmark # 806 . History . Pre - Civil War . First established after the end of the Mexican - American War ( 1848 ) , the fort was originally located in the bottoms near the Colorado River , less than a mile below the mouth of the Gila River . It was constructed to defend the newly settled community of Yuma , New Mexico Territory , located on the other side of the Colorado River , and the nearby Mexican border . In March 1851 the post was moved to a small elevation on the Colorado ' s west bank . This site had been occupied by Camp Calhoun , named for Senator John C . Calhoun . It was established on October 2 , 1849 , by 1st Lieutenant Cave J . Couts , 1st Dragoons , for the boundary survey party led by 2nd Lieutenant Amiel W . Whipple , Corps of Topographical Engineers . A ferry service , maintained by the soldiers for the survey party ' s convenience , also accommodated emigrants . Fort Yuma was established during the Yuma War to protect the southern emigrant travel route to California and to attempt control of the territorial Quechan , or Yumans , in their homeland , the surrounding area . Established by Captain Samuel P . Heintzelman , 2nd Infantry Regiment , the fort was originally named ' Camp Independence . ' In March 1851 , when the post was moved to its permanent site , its name was changed to Camp Yuma . A year later the post was designated Fort Yuma . In June 1851 the Army virtually abandoned the post because of the high costs incurred in maintaining it , and it was completely abandoned on December 6 , 1851 , when its commissary was practically empty of provisions . The post , however , was reoccupied by Captain Heintzelman on February 29 , 1852 . It was difficult to supply the post during its early years . Food supplies and construction materials were shipped by water from San Diego , California , around the Baja Peninsula and up the Sea of Cortez — Gulf of California to the mouth of the Colorado River at the Colorado River Delta in Mexico . The work of transferring the goods to wagons at that point and hauling them across the Yuma Desert and Yuha Desert to Yuma was rigorous and time consuming . Life at the post was harsh and the military ' s resolve to maintain a garrison here vacillated . Only after August 1852 did the temporary Camp Yuma became permanent Fort Yuma , and the Army resolved to stay for good . In November 1852 a steamboat , Uncle Sam was launched and in December began carrying a cargo up the Colorado River from Robinson ' s Landing it arrived at Fort Yuma and delivered thirty - two tons of goods on December 3 . Steamboats continued to supply the fort and later settlements on the Colorado River in this way until the arrival of the railroad in 1877 . Only one military action occurred at the fort when Yuman warriors surrounded it during the Yuma War , temporarily trapping the future general Thomas William Sweeny and a few others . From 1858 to 1861 the Butterfield Overland Mail had a stagecoach station near the fort , that was subsequently used by other stage lines until the advent of the railroad in 1877 . Civil War . During the American Civil War , the Union retained control of Fort Yuma when the First California Infantry replaced Regular Army soldiers sent East in December 1861 . The southern half of New Mexico Territory seceded , becoming the Confederate Territory of Arizona until 1862 when the California Column marching from Fort Yuma expelled the Confederacy , marching as far as western Texas . In 1863 the Union established their control of the region as the Arizona Territory . Fort Yuma served as the supply point for the Union garrisons there . There was no battle action at the fort since the western United States was far removed from the Civil War . Post - Civil War . Fort Yuma was closely associated with the Yuma Quartermaster Depot on the Arizona side of the river , which provided military supplies and personnel to posts throughout Arizona and New Mexico . The Quartermaster Depot operated between 1864 and 1891 , though the Army terminated most operations there eight years earlier . The depot was used by the Army to store and distribute supplies for all military posts in Arizona , Nevada , Utah , New Mexico and Texas during the Indian War period . A six - month supply of clothing , food , ammunition , and other goods was stored at the depot at all times . Supplies were brought from California by ocean vessels traveling around the Baja Peninsula to Port Isabel near the mouth of the Colorado River . There , cargos were transferred to river steamers and brought upstream to Yuma . Supplies were unloaded at the depot and hauled up a track running from the dock to a storehouse . The depot quartered up to 900 mules and crews of teamsters to handle them . The Southern Pacific Railroad reached Yuma in 1877 . There was little need for the Quartermaster Depot and Fort Yuma , and they were abandoned on May 16 , 1883 . The reservation was transferred to the Interior Department on July 22 , 1884 . Present day . Fort Yuma is now within the Quechan Indian Reservation . Numerous historic buildings remain from the military period in the Yuma Crossing and Associated Sites in the Yuma Crossing National Heritage Area . The Yuma Territorial Prison and Yuma Quartermaster Depot State Historic Park s are in Arizona with buildings preserved or reconstructed , and with museums . The Yuma Proving Grounds is the lineal Army descendant of these original military posts in the Yuma area .