In the 9th century, it was part of the defences of the Zeta principality.

But the French planned to hold out here, little expecting that it would be the first part of the defences to succumb.

Some existing buildings, including a dovecote, were reinforced and pressed into service as part of the defences.

An iron grille, part of the original defences of the door, is preserved within.

A ditch was found to be present to the east of the milecastle, possibly part of the defences.

Each small advance uncovered another part of the remaining German defences to British ground observation.

Here, too, the stream was probably used as part of the defences.

The pillbox dates from 1949 and was an important part of the defences at Montrose.

The batteries were part of the northern defences of Gibraltar.

A flooded ditch fed by water from the river protected the low-lying parts of the defences.