The Circle Fortresses of Ecthelion

The Circle Fortresses of Ecthelion are a set of five small castles that form a partial circle around the city of Ecthelion. They make a complete encirclement of the city very risky and difficult. Any army wishing to encircle the city must expose their backs to the fortresses or station more guards on each side. The fortresses are able to individually harass an enemy force. Generally each fortress recieves orders from Ecthelion, but in the event this isn't possible, each fortress has the autonomy to act independently.