Upon his death, the New York Times (where he had worked in the 1850s) wrote, "He became, in his long career, a school principal, a feature writer, a proofreader, war correspondent, dramatic critic, composer of war songs, a playwright, confidential secretary to Andrew Johnson and an officer on his staff, a major in the army, a special agent of the Treasury Department, a paymaster In the army, a Washington correspondent, special agent for the Postoffice Department in charge of the Pacific Coast, an owner of five newspapers, a volunteer fireman, one of Southern California's publicists, a great traveler, a judge of good wines, an expert in food, a noted story teller, and a man of many friends.
After a year administering a district school in Merrimack County, New Hampshire, he returned to Providence and learned typesetting.
He was a compositor and a proofreader for The New York Times from 1855 to 1859, and later worked for John W. Forney in Philadelphia at the Press, and in Washington, D.C., for the Sunday Morning Chronicle.
From Duelling in America 1992: For his book The Field of Honor (1884), Truman collected accounts of significant European and American duels that illustrated the many variations of the code duello, as it was then known.
[2] Truman owned five newspapers, including the San Diego Bulletin, where he lived for a time.