William Fletcher Wheeler was born in Warwick, New York, on July 6, 1824. After attending several New York academies, he moved to Columbus, Ohio, in 1842, at the age of eighteen. For several years he worked for the as a printer and reporter, and studied law in his spare time. In 1848 he was admitted to the bar. In 1853 Wheeler married Charlotte Jersey. Three years later the Wheelers moved to St. Paul, Minnesota, where Wheeler obtained the post of private secretary to Colonel Medary, newly appointed Minnesota Territorial Governor. Wheeler also served as territorial librarian. By September 1861 Wheeler had helped to raise a company for the Fourth Regiment, Minnesota Volunteer Infantry. He fought in the Civil War battles at Iuka and Corinth, and later was part of the Vicksburg campaign. As a result of illness, Wheeler was discharged from the service in the spring of 1864.

In June 1869, Colonel Wheeler arrived in Montana Territory as the newly appointed U.S. Marshal. He served in the position for three successive terms until 1878. During this time he was also ex-officio superintendent of the U.S. Penitentiary at Deer Lodge, Montana.

For the next decade Wheeler worked as a journalist and writer and was employed in 1884 by the Montana Historical Society to interview and write the biographies of former employees of the American Fur Company. In 1889 he accepted the position of librarian of the Montana Historical Society. He filled this post until his death in June 1894.