Horace C. Porter (1837–1921) was an American military officer, diplomat, and executive who played a prominent role in the nation's civic and political life during the late nineteenth and early twentieth centuries. He is highly distinguished for his service in the Union Army during the American Civil War, during which he held the rank of lieutenant colonel and worked as an ordnance officer and staff officer.
Porter's close association with the highest echelons of Union leadership defined much of his early career. He served as a personal secretary to General Ulysses S. Grant, maintaining this close advisory relationship during Grant's subsequent tenure as President of the United States. Porter also served as secretary to General William T. Sherman, another of the Union's most prominent military figures.
Following his military and administrative service, Porter transitioned into the private sector, where he served as the vice president of the Pullman Palace Car Company. His career culminated in international diplomacy when he was appointed as the United States Ambassador to France, a diplomatic post he held from 1897 until 1905.
