A staunch Unionist during the American Civil War, he opposed the 1861 declared secession of Mississippi from the United States.

After the end of the war, President Andrew Johnson appointed Sharkey as provisional governor of Mississippi in 1865.

[1] While he was serving as Consul, he swore in William R. King as Vice President of the United States on March 24, 1853.

Throughout the Civil War, he remained a staunch Southern Unionist and, according to one source, was "tolerated by his Confederate neighbors only because of his towering reputation as a jurist."

Governor Charles Clark appointed him in 1865 as a commissioner (along with William Yerger) to confer on behalf of the state with President Andrew Johnson.