[2] By the age of eight, Hamilton began attending a boarding school in Trenton, New Jersey, where he joined his older brother Philip studying with William Frazer, an Episcopal clergyman and rector of St. Michael's Church.
[9] He sailed to Spain in 1811 or 1812,[8][10] during a period of political conflict preceding the War of 1812, and joined the Duke of Wellington's forces, then fighting against Napoleon's army in Portugal.
[8] The 41st Regiment did not appear to have seen active service in the war,[12] and Hamilton went on to act as aide-de-camp to his father's friend General Morgan Lewis in 1814, serving until June 15, 1815.
[9] Hamilton had a "large and varied correspondence" with other political contemporaries including his close friend Henry Clay, John C. Calhoun, Salmon P. Chase, and Presidents James Monroe and Zachary Taylor.
[20] In 1833, Hamilton used funds from his mother's sale of The Grange to purchase a townhouse for her and his family in New York City, at 4 St. Mark's Place (now known as the Hamilton-Holly House).