From NKAA, Notable Kentucky African Americans Database (main entry)
Monroe, John C.
While it has long been held that all African American sailors, who enlisted in the Union Navy during the U.S. Civil War, did so stateside (within the United States borders), there are at least two cases where this is not true.John C. Monroe, born in Kentucky, enlisted in the Union Navy in Lisbon, Portugal, on June 15, 1863. He was the first of two African American sailors to enlist in Lisbon. The other sailor was Alex Thompson from New Bedford, PA, who enlisted on October 3, 1863. Both Thompson and Monroe served on the USS St. Louis. Both men may have arrived in Lisbon on board the USS St. Louis.
Monroe was about 28 years old and was a landsman with the occupation of brickmaker. It is not known if he had been enslaved in Kentucky prior to his enlistment.
The USS St. Louis was a sloop-of-war, a medium sized war ship. Starting in 1862, the ports in Lisbon, Portugal, and Cadiz, Spain, served as operation bases while the USS St. Louis was patrolling for two years in search of Confederate commerce raiding ships. The patrolled routes took the crew to and from the United States, along the African Coast, and around the Canary Islands and the Azores.
In November of 1864, the USS St. Louis returned to Port Royal, SC, to assist with the Atlantic Blockading Squadron. The USS St. Louis was decommissioned in 1865 and was sold for scrapping in 1907.
At this time, nothing more is known of John C. Monroe's life before or after his military service.
* Further research shows that there were many more than two African American sailors who enlisted in the Union Navy outside the U.S. borders. These men enlisted in countries such as Brazil, Mexico, and Panama. Their names can be found in the African American Civil War Sailors Index, 1861-1865 (Ancestry).
Sources: See John C. Monroe, Sailor Detail at the National Park Service, The Civil War website; see Alex Thompson, Sailor Detail at the National Park Service, The Civil War website; USS St. Louis (1828), a Wikipedia webpage.