A garrison is a group of soldiers stationed in a particular place to defend it, or the military post where they're based. When a country wants to protect a fort, city, or strategic location, they garrison it by sending troops to live and work there. The soldiers who make up a garrison might number anywhere from a few dozen to several thousand, depending on the importance of the location.

Throughout history, garrisons protected everything from remote frontier outposts to major cities. Roman soldiers garrisoned Hadrian's Wall in northern England for nearly 300 years, watching for threats from the north. During the American Revolution, British troops garrisoned major colonial cities like Boston and New York. A garrison's responsibilities include fighting when necessary, but also maintaining their fort, training, patrolling the area, and showing potential enemies that the place is defended.

The word can also be used as a verb: to garrison a fort means to station troops there. A garrison town grew up around a military base, with shops and homes built to serve the soldiers and their families. Even today, military bases around the world function as modern garrisons, housing troops that protect important locations and respond quickly to threats.