Fort Cassin, also spelled as "Fort Cassin," is a historical fort located in Ferrisburgh, Vermont, USA. It was constructed during the War of 1812, a conflict between the United States and Great Britain. The fort was named after Captain Lewis Cassin, a U.S. Navy officer who was killed in action during the War of 1812.

Fort Cassin was strategically positioned on Lake Champlain to defend against potential British invasions from Canada. It consisted of earthworks and wooden palisades, typical of fortifications of that era. The fort played a role in the defense of the northern frontier during the war.

One notable event involving Fort Cassin occurred in 1814 during the Battle of Plattsburgh. The British launched an invasion from Canada, aiming to capture key positions along Lake Champlain. American forces, including Fort Cassin's defenders, played a crucial role in repelling the British assault, contributing to the American victory in the battle.

After the War of 1812, Fort Cassin lost its military significance and fell into disrepair. Today, the site of Fort Cassin is preserved as a historic landmark, providing visitors with insights into the military history of the region and the role played by fortifications like Fort Cassin during the early 19th century.