Camp Cooke ( Montana ) Camp Cooke also known as Fort Claggett as a U . S . Army military post on the Missouri River in Montana Territory . The camp was established on July 10 , 1866 , just upstream from the mouth of the Judith River by the 13th Infantry Regiment . By 1867 , Camp Cooke had a strength of approximately 400 men . The army established the post to protect steamboat traffic en route to Fort Benton , which carried passengers and freight to supply swiftly growing boom towns at the site of rich gold strikes in the western mountains of the Montana Territory . However the location of the fort was along the upper Missouri River , as it crossed the broad eastern plains of Montana , far from the gold camps and their boom towns in the western Montana mountains . The fort was also located deep in the remote badlands , called the Missouri Breaks , which paralleled the Missouri River for hundreds of miles , Once the fort was constructed , the garrison had little to do . Except for the high water months of May , June and July , Missouri River steamboat traffic was limited . As a result , soldiers were dispatched from Camp Cooke to other more strategic locations in the Montana Territory . Detachments from Camp Cooke guarded major transportation routes in Southwestern Montana , including the roads between Fort Benton and Helena . They built Fort Shaw along that route in 1867 in the Sun River Valley . Other detachments from Camp Cooke built Fort Ellis near Bozeman , Montana in the upper Gallatin Valley , which guarded the critical east - west over land route over Bozeman Pass . Camp Cooke was abandoned less than four years after it was built on March 31 , 1870 , in response to constant well - founded complaints that the location of the post was too remote . Purpose of Camp Cooke . The purpose of Camp ( Fort ) Cooke was to provide protection to Missouri River traffic and settlers in the Montana Territory who were traveling up the Missouri to the goldfields . Following the gold strikes at Bannack , 1862 ( Grasshopper Gulch ) ; Virginia City , 1863 ( Alder Gulch ) ; Helena , 1864 ( Prickly Pear Creek and Last Chance Gulch ) ; and the spectacular gold strikes in 1865 at the Montana Bar and other sites in Confederate Gulch , immigrants poured into the Montana Territory . The gold fields were in the western mountains of Montana , in the intermontane valleys . The immigrants had to cross the extensive eastern Montana plains , to reach the gold fields . The primary access route to the gold fields was up the Missouri River by steamboat to the head of navigation at Fort Benton . A secondary route for overland travelers was over the Bozeman Trail which branched off from the Oregon Trail in Wyoming Territory , skirted the eastern edge of the Big Horn Mountains after which the trail continued up the Yellowstone River valley to reach the Montana goldfields via the Bozeman Pass . Settlers and miners traveling to the Montana goldfields crossed territory that Indian tribes considered theirs . These lands were occupied by the Blackfoot , Gros Ventre , Assiniboine , Lakota Sioux , Northern Cheyenne , and Crow tribes . The Missouri River steamboats and the resulting freight routes fanning out from the Missouri River , and the overland immigrant trains coming up the Bozeman Trail , drove off the buffalo and other game on which the Indian depended . In reaction , the Indians retaliated by mounting small scale , scattered , guerrilla type attacks and raids . The Indians attacked steamboats and freight wagons . They attacked parties of overland immigrant and mail carriers . They stole livestock and killed travelers and settlers as opportunity presented . First army post in Montana Territory . As reports of thefts of livestock and killings by Indians accumulated , the newspapers that had sprung up in the swiftly growing mining and trading communities of the Montana Territory demanded that the U . S . Army provide protection . Petitions and letters went east to Washington . In response the army established Camp Cooke on the Missouri River in the Montana Territory on July 10 , 1866 . To protect the Bozeman Trail , the army had established forts in Dakota Territory at Fort Reno ( 1865 ) and Fort Phil Kearny ( 1866 ) . On August 12 , 1866 , the army established Fort C . F . Smith on the Big Horn River just inside the boundary of Montana Territory . Thus , by the narrow margin of one month , Camp Cooke became the first U . S . Army post in the Montana Territory . Naming Camp Cooke . Camp Cooke was named in honor of Brig . Gen . Philip St . George Cooke . In 1866 he was in command of the Department of the Platte , which then included the Montana territory . Locating Camp Cook . Inspector General D . B . Sackett was sent to Montana to select a site for the military outpost to protect the traffic on the Missouri River . The logical site was Ft . Benton , the head of navigation on the Missouri River . However Sackett judged that Ft . Benton had sufficient resources to defend itself , and the considered the area lacked materials for the construction of a post , and also lacked sufficient range for the maintenance of its livestock . He recommended a site at the mouth of the Musselshell River , where a small community existed . As an alternative Sackett suggested the mouth of the Judith River . Remote location of Camp Cooke . The Montana Territory gold strikes were located in the intermontane valley region of western Montana , far removed from Camp Cooke . Camp Cooke was in the broad - reaching eastern plains of Montana . Geographically the post was isolated from the western part of the territory . Further , the post was located deep within a several hundred mile stretch of the Missouri River known as the Missouri Breaks , which are steeply eroded badlands bordering the river and separating it from the surrounding eastern Montana plains . Protect river traffic . Camp Cooke was located on the south side of the Missouri River , just upstream from the mouth of the Judith River . This location was along the Missouri River , a major artery of commerce from the early 1860s to the late 1880s . In this period steamboats brought traffic and passengers to Ft . Benton in the Montana Territory . Ft . Benton was the head of Missouri River navigation in the Montana Territory . However steamboat traffic on this section of the Missouri was limited to a few months of " high water " , which occurred when seasonal runoff of snow melt from the prairies and mountains of Montana made upriver steamboat navigation to Fort Benton possible . Except for the months of May , June and July , steamboat traffic was virtually nonexistent . Downstream from Camp Cooke was the Dauphine Rapids , which were difficult - to - impossible to traverse after the river began to fall , after the spring floods . During low water season on the Missouri , most freight and passengers were offloaded down stream from Camp Cooke , at Cow Island and carried by freight wagon to Ft . Benton . These freight routes did not pass by , or even close to Camp Cooke . Abandonment of Camp Cooke . Because of its isolation Camp Cooke was abandoned on 31 March 1870 , although a rapidly growing infestation of rats at the post helped prompt the decision . Visiting the Site of Camp Cooke . The Missouri Breaks have resisted settlement and so the site of Camp Cooke remains remote to this day . The site cannot be easily visited . It can be reached by canoeing / floating down the river through the Missouri Breaks , in the section now designated a wild and scenic river and part of the Missouri Breaks National Monument . the site of Camp Cooke is located at River Mile 86 . 8 Right . Today there are only the foundations of some of the buildings and the usual rubble that survives after the buildings were taken away , torn down or simply deteriorated and fell in . Sources . Huckabee , Rodger Lee , " Camp Cooke : The First Army Post in Montana – Success and Failure on the Missouri " ( 2010 ) . Boise State University Theses and Dissertations . Paper 153 .