Rowan was born in Gap Mills, Virginia in 1857. He enrolled at West Point at the age of twenty and was commissioned a second lieutenant in 1881. In the years before the Spanish American War, Rowan served several frontier posts and with military intelligence in Latin America. He was interested in Cuba in particular and co-wrote a book about the island (see writings listed below).
With tensions between the United States and the Spanish (who then ruled Cuba) growing, President William McKinley saw value in establishing contact with the Cuban rebels who could prove a valuable ally in case of war with Spain. McKinley asked Colonel Arthur Wagner to suggest an officer to make contact with Garcia's rebels. Wagner suggested Rowan who then traveled to Cuba via Jamaica. Rowan met Garcia in the Oriente Mountains and established a rapport. Rowan garnered information from Garcia who was eager to cooperate with Americans in fighting the Spanish. Rowan returned to the US and was given command of a force of "Immunes", African-American troops assumed to be immune to tropical diseases found in Cuba.
In 1899 artist and publisher Elbert Hubbard wrote a passage entitled A Message to Garcia extolling the virtues of Rowan and urging Americans to unquestioningly follow any directive. Finding appeal in this message, industrial and military leaders ordered millions of copies of the text to distribute to their workers and soldiers making it a best-seller. It was translated into several languages and sold internationally.
In 1908, while Rowan was commander of Fort Douglas, Utah, his wife, Josephine, established a reading room for the blind at the Salt Lake City Library. This may be the longest, uninterrupted, service project in the city's history.