An additional fort was built in 1701 called Fort Blanc.

Two additional forts, somewhat distant from Marietta, were also built by settlers from the Ohio Company of Associates.

He established additional forts that aimed to supply a land route to Zacatecas in present-day Mexico, where the Spanish had silver mines they wanted to protect.

An additional fort near Pfuhl was planned in the mid-1860s, but cancelled due to the dissolution of the German Confederation.

After the British defeat at the Battle of Plattsburgh, two additional forts were added near Forts Brown, Moreau, and Scott.

In June 1940 additional forts were added to the camp to accommodate British soldiers.

After encounters with English ships on the Lower Mississippi, Iberville ordered Bienville to construct an additional fort.

In addition to the main fortress, two additional supporting forts, redoubts, were built in the vicinity.

An additional, short-lived, fort was built in 1552 to supplement the walls.

These additional forts were Newbrough, Magnis (Carvoran) and Brampton Old Church.