William Meade Fishback was born in Jefferson, Virginia. He graduated with a law degree from the University of Virginia in 1855. He moved to Illinois where he was admitted to the bar in 1857.
In 1858 Fishback moved to Greenwood, Arkansas. In 1861 he was elected to the Arkansas Secession Convention as a pro-Union delegate. Fishback established a pro-Union newspaper called The Unconditional Union in 1863. During the American Civil War he raised 900 troops for the 4th Arkansas Cavalry Regiment (USA) and served as Colonel.
He was selected to represent Arkansas in the United States Senate in 1864 but was not allowed to take his seat.
Fishback was a delegate to the 1874 Arkansas Constitutional Convention. He served as a member of the Arkansas House of Representatives from 1871 to 1881. Fishback introduced what came to be known as the "Fishback Amendment" to the state constitution. This amendment prohibited the state authorities from paying the Holford railroad aid and levee bonds. Failure to pay the Holford debt created credit problems for the state that lasted well into the 20th century.
On 5 September 1892 Fishback was elected as Governor of Arkansas. Fishback's administration focused on changing the national image of the state. During his term the St. Francis River levee district was formed.
Fisbhack served as governor until 1895 when he left public office and worked attempting to attract business to the state.
William M. Fishback died of a stroke. Fishback is buried at Oak Cemetery in Fort Smith, Arkansas.