Walker was born on October 19, 1822, in
Franklin County, Pennsylvania. After marrying Marian E. Lowe in 1842, Walker moved to
Ohio in 1848, and worked there as a cabinet maker. In 1855 he settled permanently in
Lawrence, Kansas. There Walker became a founding member of the Bloomington Guards, a local militia company, in late 1855, and he was quickly elected
first sergeant. In the following year Walker was elected
colonel of the 4th Kansas Cavalry, which participated in all the campaigns of the free-state men during
Bleeding Kansas. In that capacity Walker was present at the sieges of Lawrence and Fort Saunders, and commanded free-state forces on August 16, 1856, at the
Battle of Fort Titus, which was a free-state victory. In 1856 Walker served as a member of the short-lived Territorial House of Representatives under the
Topeka Constitution, and around the same time he also was a Deputy U.S. Marshal. Walker became the sheriff of
Douglas County, Kansas, in October 1857 and served until January 1862. ==Civil War==