He attended a private academy, and engaged in mercantile pursuits until the American Revolutionary War, at which time he served as captain, major, and lieutenant colonel in the Continental Army.

Prior to the American Revolutionary War, as a young captain, he was sent to Annapolis to arrest Governor Eden and seize his papers.

[2] On September 23, 1776, with the Revolutionary capital of Philadelphia on the verge of capture by the British, Washington sent Smith, then a Lieutenant Colonel of the 4th Maryland Regiment, with a Continental Army detachment into the fort on Mud Island on the Delaware River.

[6] With the British army closing in on Philadelphia, the small force had to reach Fort Mifflin by a circuitous route.

On the last leg of their journey, reinforcements for Mud Island had to be ferried across the Delaware from Red Bank, New Jersey under the protection of the Pennsylvania Navy river flotilla commanded by John Hazelwood.

As a principal negotiator between the young Federalist leader and Delaware representative, James Asheton Bayard II, and the presumptive President-Elect Jefferson, Smith secured the winning ballot in the United States House of Representatives for Jefferson during the 1800 United States presidential election.

On December 17, 1822, Smith resigned as congressman, having been elected as a Democratic-Republican (later Crawford Republican and Jacksonian) to the United States Senate to fill the vacancy caused by the death of William Pinkney.

Samuel Smith, a distinguished American politician and military leader, died on April 22, 1839, at his residence, Montibello, near Baltimore, Maryland.