fort

Iron Age, Roman, Saxon, etc.

The archaeologists discovered pottery fragments from a Roman fort in the valley below.

hold

While the manager was away, the assistant had to hold the fort at the office.

be/come under attack, be/come under siege

The old fort came under siege during the war and had to surrender.

fall

The ancient fort fell to enemy forces during the final battle of the war.

at/in a/the ~

The soldiers worked hard to repair the damaged walls in the fort.