During the negotiations, the British had four invasions underway. One force carried out a burning of Washington, but the main mission failed in its goal of capturing Baltimore. The British fleet sailed away when the army commander was killed. A small force invaded the District of Maine from New Brunswick, capturing parts of northeastern Maine and several smuggling towns on the seacoast and re-established the New Ireland colony with the ultimate purpose of incorporating Maine into Canada. Much more important were two major invasions. In northern New York State, 10,000 British troops marched south to cut off New England until a decisive defeat at the Battle of Plattsburgh forced them back to Canada. The defeat called for a court-martial of the commander. Nothing was known at the time of the fate of the other major invasion force that had been sent to capture New Orleans and control the Mississippi River.