Owing to his father's career as a judge, Monroe managed to become an attorney during the 1850s.

[1] Around the time, Monroe was promoted to colonel on December 12, 1862, and was given command of the regiment.

[3] Monroe and the 22nd Kentucky went on to participate in Ulysses S. Grant's Vicksburg campaign as they saw service at Arkansas Post, Thompson's Hill, Champion Hill, Big Black River Bridge and various other battles.

[2] On March 18, 1865, President Abraham Lincoln himself brevetted Monroe to Brigadier General for "gallant and meritorious services during the war" and for the Union cause.

[2] Monroe continued to serve in the United States Army after the war as Kentucky's Quartermaster General until September 1868 when he was forced to resign due to sickness and died on September 22, 1869, and was buried at Frankfort Cemetery.