The Hartford Convention was held by delegates from different states who opposed the War of 1812. Some convention participants demanded secession from the Union. In the end, the convention just called for constitutional amendments limiting the power of the Presidency.
Many in the Northeast continued to oppose the War of 1812. A minority of New Englanders called for secession from the Union. New England was suffering from the sea blockade imposed by the British in 1814. As a result, a convention was held in Hartford, Connecticut to unite the opposition to the war and develop a common platform. Delegates from Massachusetts, Connecticut and Rhode Island convened in Hartford from December 15, 1814 to January 5, 1815.
A number of the radical Federalists at the convention called for the secession of the New England states from the Union. The majority, however, voted for a platform demanding a change in the Constitution, requiring two-thirds vote by Congress to impose an embargo; admit a Western state into the Union or begin a war, except in the case of an invasion.
By the time the delegates of the Hartford Convention arrived in Washington; the news of the victory of New Orleans, followed by the Treaty of Ghent, made their demands seem absurd.