Small defensive forts built in several countries of the British Empire during the 19th century, from the time of the Napoleonic Wars onwards.
They stand up to 40 feet (12m) high (with two floors) and typically had a garrison of one officer and 15-25 men. They were used throughout the 19th century, but became obsolete with the introduction of powerful rifled artillery.
Howth Harbour, Co. Dublin
