Barney served in the Continental Navy beginning in February 1776, as master's mate of Hornet where he took part in Commodore Esek Hopkins's raid on New Providence.

In April 1782, he was put in command of the Pennsylvania ship Hyder Ally, in which he captured the British sloop-of-war HMS General Monk in the Battle of Delaware Bay.

[2][4] He was given command of Monk (renamed General Washington) and sailed for France with dispatches for Benjamin Franklin, returning with news that peace had been declared.

He authored the plan to defend the Chesapeake, which was submitted to Secretary of the Navy, William Jones and accepted on August 20, 1813.

The British, frustrated by their inability to flush Barney out of his safe retreat, instituted a "campaign of terror," laying waste to "town and farm alike" and plundering and burning Calverton, Huntingtown, Prince Frederick, Benedict and Lower Marlboro.

[10] The British, under the command of Admiral Sir Alexander Cochrane then moved up the Patuxent, preparing for a landing at Benedict.

Leaving his barges with a skeleton crew under the command of Lieutenant Solomon Kireo Frazier to handle any destruction of the craft, Barney took the majority of his men to join the American Army commanded by General William Henry Winder where they participated in the Battle of Bladensburg.

[10] During the Battle of Bladensburg, Barney and 360 sailors and 120 Marines defended the national capital—fighting against the enemy hand-to-hand with cutlasses and pikes.

The defenders were forced to fall back after nearly being cut off, and the British went on to burn the Capitol and White House.

[13] During the battle, President James Madison personally directed the Marines led by Barney.

This battle is one of only two instances of a sitting president exercising direct battlefield authority as Commander-in-Chief, the other being when George Washington personally crushed the Whiskey Rebellion.

[14] Commodore Barney died in Pittsburgh, Pennsylvania on 10 December 1818 en route to Kentucky, from complications related to the wound he received at the Battle of Bladensburg.