How did the war of 1812 and the hartford convention affect the federalist party?

Ended the party--in the War of 1812, the northern Federalists lost trade with Great Britain.

Federalists believed the US must become an industrial country not a farming country. The Hartford Convention was a discussion of New England states leaving the Union. When the war ended, they no longer needed to leave because they could trade with Great Britain again and the country now were united in creating an industrial country with a national banking system. The Federalist party disappears and the US is a one party country until the 1828 election.