The pretext for all this havoc was a raid made by a few American troops who had crossed to Long Point on Lake Erie, May 15, 1814, and had burned some Canadian mills and a few dwellings.

The expedition was promptly disowned by the American Government as unauthorized, but in retaliation the British navy was ordered to lay waste all towns on the Atlantic coast which were assailable, sparing only the lives of the unarmed citizens.
Included in the British plan of campaign for 1814 was a coastal attack important enough to divert American efforts from the Canadian frontier.
This was why an army under General Ross was loaded into transports at Bermuda and escorted by a fleet to Chesapeake Bay.

The raids against small coastwise ports, though lucrative, had no military value beyond shaking the morale of the population.

The objective of this larger operation was undecided.

Either Baltimore or Washington was tempting.
But first the British had to dispose of the annoying gunboat flotilla of Commodore Joshua Barney, who had made his name mightily respected as a seaman of the Revolution and who had never been known to shake in his shoes at sight of a dozen British ensigns.