Horace Porter was born April 15, 1837 in Huntington, PA (United States of America), the son of David Rittenhouse Porter (1788-1867), a two time governor of the State of Pennsylvania. D. Rittendhouse Porter was the grand-uncle in law of President Abraham Lincoln. Horace Porter's grandfather distinguished himself as a U. S. Revolutionary War general (1776). (see Porter genealogy)
Horace Porter served as a Captain in the Union Army, and as an aide-de-camp to General Ulysses
S. Grant during the U.S. Civil War (1864-65). Porter accompanied Grant into battle at Cold Harbor, the Wilderness, and the Petersburg campaign.
Throughout the war, Porter kept extensive notes of the campaigns, and he was present at General Lee's surrender at McLean's house on April 9, 1865. Later, his
first-hand accounts and analyses were published as "Campaigning with Grant" by General Horace Porter.