The following sources deal with the issue of the feasibility of the coastal defences of the 18th Century. Source A is taken from on of the volumes of the Archives while Source B is taken from a book on Military History.
Source A: "…but because these are so many and these need a great number of cannon and soldier to defend… its better to leave those which are far away that is those of the bays of Mellieha (Bay) and St. Paul's (Bay) because they are so dangerous and at the same time the natural entrenchment of the valley called Wied il-Ghasel…" (Archive of the Order, Volume 267 Pg. 124, written in 1722).
Source B: "As a result, should an attack take place, the works to the north of the Great Fault were to be abandoned while the troops were to hold the three routes up through the valley, defended by entrenchments at Falca, Naxxar, and Bingemma…" (Stephen C. Spiteri, Fortresses of the Cross, published in 1994).
Below: A side view of one of the remaining parts of the Inland Entrenchment found at Naxxar.