In the US Army a fort is a permanent post. It also refers to a hrbor and its attendant fortifications. A fortress is a large permanet fortification that my include a town. A camp is a temporary post. Barracks are permanent troop billets while a cantonement is (in US usage) a temporary billet.
The other services frequently use the term base or station intead of fort.
The USMC has camps because they are an expeditionary force and "soldiers of the sea" and have no permanent installations.
For the most part installations are now named after heroic individuals or local personages. So were the attendant batteries, etc in harbor fortifications.
James B. Ronan II
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