Henry Hobart Mason was born on April 26, 1832, in Poultney, Vermont, to Darwin and Cornelia Mason. He grew up and attended school in Canandaigua, New York, before enrolling at Hobart College. He earned a Master’s degree from Hobart in 1857. He moved to Wisconsin in the late 1850s, reportedly with plans to enter the ministry. According to an early biographer, he soon “gave up this study and took up the study of law.” He moved to Crawfordsville, Indiana, and began practicing law.
In the fall of 1862, he received a commission as a 1st lieutenant in the 2nd New York Cavalry. The regiment took part in the Second Battle of Manassas, the Battle of Fredericksburg, and the Battle of Gettysburg. He reportedly “made a brave officer and had a fine war record.” He was promoted to captain in January 1863. Confederate forces captured him in September 1863 while he was on picket duty, and he spent the next six months as a prisoner of war. He mustered out on September 10, 1864.
He moved to Lafayette, Indiana, after leaving the army, and he worked as a newspaper writer. He eventually moved to New York City and worked for the New York Tribune. He later became a district court clerk. He married Mary Trowbridge on April 27, 1893. They moved to Great Barrington, Massachusetts, around 1896, and he died there of heart disease on August 12, 1901.