[6] During the U.S. Civil War, Morris enlisted as a private in the Union Army, Company K, 7th Infantry, New York Regiment on June 1, 1862 and he mustered out on September 5, 1862.
[8] The regiment was known as a "Silk Stocking" regiment and "Blue-Bloods" due to the disproportionate number of its members who were part of New York City's social elite,[9] In 1864, he was acting Medical Cadet at Sand's Island and in 1866, he served as acting Assistant Surgeon at Hart and Davids Island during the fourth cholera pandemic.
[14] On December 10, 1868, he married Ellen James "Elly" Van Buren (1844–1929) at Saint Mark's Church in New York City.
About this time Alice James remarked acidly that Elly's flustered carryings - on about her engagement were likely to exasperate her fiancé beyond endurance.
In 1913, Henry, writing to his acolyte Howard Sturgis about the relatives he had mentioned in his memoir A Small Boy and Others, explained enigmatically, 'Yes, my Father's two other sisters were my Van Buren and my Temple aunts.
In January 1902 William James wrote to Henry during a visit to the United States, 'I also saw Elly Van Buren, old looking but unaltered in manner.
[30] His donation, along with that of Mrs. Smith Thompson Van Buren, his mother-in-law, rendered the Library "a remarkably full one of political documents bearing upon the middle period [as of 1907] of the history of the United States.