Forts were fortified locations typically garrisoned by the military forces of the owner.
During the early 18th century, the pirate Edward Kenway assaulted and captured ten forts under the control of either the Royal Navy or Spanish Navy throughout the Caribbean, whereas during the Seven Years' War, Templar Shay Cormac captured forts under control by the French Navy throughout the Northern Atlantic Ocean and River Valley. During the American Revolutionary War, Edward's grandson, the Assassin Ratonhnhaké:ton, captured several forts under the control of the British Army, located in Boston, New York, and the Frontier.
When Kenway or Cormac assaulted a fort, they first used their ship's cannons to destroy all of the outer walls and towers, rendering the fort vulnerable. They would then infiltrate the fort itself, kill its officers, destroying powder reserves, and break into the war room, where they would dispatch the commander. In the case of Edward taking over, the fort's flag would be lowered and replaced with a black one, and served as outposts for pirates in the nearby waters. When taken over by Shay, the flag would be replaced by a British one. 
In Colonial America, after destroying a fort's gunpowder reserves and killing its captain, Ratonhnhaké:ton lowered the British flag in exchange for a Colonial one. By doing so, control of the fort shifted from British control to that of the Continental Army.
By capturing the forts in the Caribbean, Edward was able to exert his piratical influence over a much greater area, as the forts would attack any passing warships. In addition, capturing a fort would clear away a part of the map, detailing previously undiscovered locations. In the Thirteen Colonies, capturing the forts helped make the trade routes much safer, as previously there had been a higher risk of losing trade vessels, such as convoys, to bandits.
- Cabo de Cruz – Caribbean Sea
- Castillo de Jagua – Caribbean Sea
- Charlotte – Caribbean Sea
- Chinchorro – Caribbean Sea
- Conttoyor – Caribbean Sea
- Dry Tortuga – Caribbean Sea
- Eleuthera – Caribbean Sea
- Gibara – Caribbean Sea
- Navassa – Caribbean Sea
- Punta Guarico – Caribbean Sea
- Serranilla – Caribbean Sea
- Castillo de la Real Fuerza – Havana
- Castillo de San Salvador de la Punta – Havana
- Castillo Morro – Havana
- Fort Charles – Port Royal
- Fort Nassau – Nassau
- Fort St-Mathieu – Frontier
- Fort Monmouth – Frontier
- Fort Duquesne – Frontier
- Fort Hill – Boston
- Fort Independence – Boston
- Southgate Fort - Boston
- Fort Washington – New York
- Fort Division – New York
- Fort George – New York
- Fort Arsenal – New York
- Fort Phoenix – Martha's Vineyard
- Fort Wolcott – Goat Island
- Fort St-Jean – Quebec
- Port La Joye – Atlantic Ocean
- Fort Baie Rouge – Atlantic Ocean
- Fort Louis – Atlantic Ocean
- Anticosti – Atlantic Ocean
- Fort de Sable – Atlantic Ocean
- Fort Blanc – River Valley
- Fort La Croix – River Valley
- Fort Soleil – River Valley
- Fort Saint-Jean – Louisiana
- Forts replaced Borgia Towers from Assassin's Creed: Brotherhood and Assassin Dens from Assassin's Creed: Revelations.
- Liberating forts allowed Shay, Edward and Connor to use them as fast travel points.
- When used as a fast travel point by Connor, a liberated fort would occasionally spawn a single British soldier, who would then be killed by the fort's Continental soldiers.
- When warships would pass captured forts in Assassin's Creed IV: Black Flag, they would be fired upon by the fort's cannons, although no military force would appear manning the cannons after the fort was captured.