Ellis County, Kansas
Fort Fletcher, named for Missouri Governor Thomas C. Fletcher, was established on October 11, 1865. It was located 14 miles southeast of present day Hays. Some time during the winter of 1866-67, the name was changed to Fort Hays, in honor of Major General Alexander Hays, who had been killed in 1864 during the Civil War Battle of the Wilderness. (see note below) A flood on Big Creek on or about June 3, 1867 prompted the relocation of the Fort to near present day Hays.
The fort was established to provide protection to the railroad builders and settlers who were moving into central and western Kansas. Fort Fletcher was located on the Smoky Hill Trail, a stagecoach road to Denver and later the route of the Kansas Pacific Railroad.
A note about Major General Alexander Hays
You make run across some documents which state that Fort Fletcher was renamed to Fort Hays in honor of Major General Issac G. Hays. These documents appear to be in error.