Pirate incursions (or Razzias) on the Maltese Islands were a constant problem from the 14th Century onwards. In the Middle Ages to provide a warning system against any razzia a local militia was established. It was called the Dejma. The first surviving evidence of the Militia List is that of 1419 found by Prof. G. Wettinger. There is no evidence however that there were any coastal towers.
The first of the coastal fortifications were built by Grand Master Aloph de Wignacourt in 1610. A total of seven towers were built by Alof de Wignacourt at St. Paul Bay (1609), Marsaxlokk (St. Lucianís Tower - 1610), St Thomas Bay (1614), Marsalforn (Gozo - 1616) Comino (St. Maryís Tower - 1618), and Sta. Maria Delle Grazie (1620). These towers were large squarish structures which were more like small forts in form and use rather than simple lookout posts. These massive structures were built to dominate the coastline, mounting batteries of heavy artillery on their roofs and garrisoned by sizable detachments in times of war.
Here again the concept of cause and effect is so evident: St. Thomas' Tower (Marsascala) was built after a Razzia because it exposed the limitations of the defence of that area.
After the death of Grand Master Wignacourt in 1621, the defence focused again on the Harbour. Grandmaster Lascaris amongst the major defence programs focused again on creating a network of communication using smaller towers. Two coastal watch towers were built (at Gnejna and Ghajn Tuffieha) which were able to communicate with another tower at Bingemma which is turn is visible from Mdina.
The capture of the Sultana Ottomana (to be discussed in one of the coming lessons) triggered a sense of insecurity among the knights. The response was the building of a new large tower (Red Tower) on the highest point of Marfa Ridge.
It was grandmaster Martin De Redin who took very seriously the issue of creating a link of communication between Malta and Gozo using Coastal Watch Towers. 13 towers were built in 1658. The Maltese benefited most from this measure as the Militia (still functioning from the Middle Ages) could have better lookout post.
It was during the reign of Grand Master Perellos when the threat of an invasion by Turks was imminent that the Knights brought over a number of French Engineers to study how they can improve the coastal defences.
They proposed to build three types of fortifications to enhance the coastal defence. These were the Batteries, the Redoubts and the Entrenchments
Ironically the batteries which were designed to protect and repel an invasion from any Moslem attack were never used. When there was the need to use them in 1798 the half-hearted attempt to stop the French failed miserably. This leads us to think about the feasibility of this defensive scheme. Just think about; was it worth the money spent when they did not have enough soldiers to defend it.
Prof. V. Mallia Milanes argues that these coastal fortification schemes were just an afterthought on defence issue as for the Knights the only important location was the Grand Harbour otherwise the rest of Malta was unimportant. Whether one agrees or disagrees with his point is at your own judgment.