1. A group of soldiers or military troops stationed in a fort, town, etc., to defend it: American troops are assigned to garrisons in other countries besides those that are in the United States.
2. Etymology: from Old French garison, "fortification"; formed from garir, "to defend"; ultimately from a prehistoric German word meaning "to protect".

The sense of "fortress" and then of being a "detachment of troops" in a garrison developed in the 15th century.

To provide a fort or base in or near a town with a military post and troops: Many U.S. soldiers and airmen are garrisoned in other nations with their families and special facilities; such as, libraries, food centers, schools, etc.