When the Maltese islands were under the rule of the Aragonese, the local government or the Universita’, had the responsibility of defending the coasts. But the Universita faced a large problem, that of not having enough men to keep the watch-posts. This critical situation is mentioned for the first time in 1399. The lack of men to keep the watch-posts resulted in many attacks by the Moors, which often resulted in the taking of many Maltese into slavery.
However, efforts were made to organise an efficient watch around the coast-line. The best examples of these attempts are the Militia Lists of 1417 and 1419-20, which were published by Profs Godfrey Wettinger. From these lists we know that in Mellieha, for example, there were at least three watch-posts; one at Ghajn Tuffieha, one at l-Ahrax and the last one at Ir-Ramla. Here, il-Mahras (Coastal Watch) maintained coastal watch in summer time, where there was a probability of an invasion by the Muslims because of the good weather.
Both on Ghajn Tuffieha and id-Dahar there are references of Burgio or Borg. In the former the land where the Hospitallers’ built their tower is referred as Borg. This is an indication that there were the remains of a building, probably a tower. At id-Dahar too there is a reference, this time Burgio torre, with a probability that there was a medieval tower. In these two places the Universita of Mdina maintained coastal watch, where il-Mahras kept watch there.
In 1375, an official was appointed to organize a network of watch-posts across the island. The guards would watch for attacks by the Moors and later the Barbary Corsairs and Ottoman Turks. Some 24 watch-posts were set up around Malta to send warning messages to Mdina and the Castrum Maris (known today as Fort St Angelo).
The Order of the Knights of St John built on this system in the 17th Century with a series of Coastal Watch Towers, When the Hospitallers arrived in Malta, in 1530, they did not build towers. It took at least a century for the Hospitallers to build towers. We have to bear in mind that during this period the most important type of coastal fortification was the tower. In fact many of the Mediterranean countries of this period built coastal towers.
The system of coastal towers was developed more technically by the Spaniards, in Spain and their colonial possessions. Until 1567, in Naples, Pietro de Toledo, the Spanish viceroy, built some 313 coastal towers throughout the Neapolitan kingdom. In Sicily Ferrante Gonzaga, the Spanish viceroy built from 1535 and 1543 some 137 coastal towers. The Spanish began refortifying their possessions because they found them too weak to resist any Turkish assault.