Since the Middle Ages the Maltese islands were open to frequent attacks by corsairs from the Barbary coast. Many young Maltese and Gozitans were captured by the Moslems and carried into slavery.

Before the coming of the Knights, coastal defences were non-existent and there was nothing to prevent the raiders from disembarking on these shores.

The Knights realised the seriousness of the situation, and at once set about to fortify the harbour area and other vulnerable points.

At a later period they erected castle-like towers, e.g. St. Lucian and St. Thomas in the south, and similar ones in other strategic places.

In 1657, the Aragonese knight Martin de Redin, was elected Grand Master, and his traditional 'gioia' or gift to the Order, was his undertaking to construct, at his own personal expense, 13 watchtowers to re-inforce the defences of the coastal areas. The work was completed within two years and the towers came to be known as the De Redin Towers.

The towers consist of a quadrilateral structure of solid masonry with two storeys. They were built in such a way that each tower was within sight of the next so that when one tower saw approaching a raiding party far out at sea, the signal was passed to the next tower and started a chain alert from one point to the next. A garrison could thus be prepared in time to meet the raiders. Signals were given from the roofs by means of smoke during the day and by bonfires during the night.

The towers were manned by the Dejma - the local militia who were paid a small wage. The thirteen towers extend from Marfa - the extreme north east point - to Delimara in the south east, and then to the south up to Wied iz-Zurrieq, where the coast turns into steep cliffs and no additional towers were considered necessary.

When Moslem raids became less frequent in the 18th century, the towers were no longer manned and they fell into disuse.