A cannon is a large hollow tube designed to use gunpowder to hurl an object at a target. The earliest mention of cannon is their use in the siege of Metz in 1324. Only slightly later is another reference in a surviving Florentine document of 1326 referring to "pilas seu palloctas ferreas et canones de mettallo", indicating a bronze cannon firing iron balls. A definite reference to cannon occurs that same year in a manuscript of Walter de Milemete's. By 1350 Petrarch wrote "these instruments which discharge balls of metal with most tremendous noise and flashes of fire...were a few years ago very rare and were viewed with greatest astonishment and admiration, but now they are become as common and familiar as any other kinds of arms." The primary uses of early cannon were as bombards to knock down the walls of besieged towns and castles. The earliest success at this came in 1377 at the siege of Odruik when cannon firing 91 kg (200 pound) balls breached the walls of the castle. Cannon underwent rapid evolution in both size and construction. They quickly became large and almost as quickly became small, evolving into hand weapons as well.
The Knight immediately started to build up their stock of ordnance which came in various sizes and formats. One notable mention is the basilisks brought over by the Turks in 1565. The basilisk was a large cannon capable of firing a shot of 160 pdr. The Knights bought many beautiful decorated bronze cannons during their prolonged stay. However most of the cannons were made of iron which is cheaper and less durable.
Guns are a major component of a fort and in particular cases the forts were built on purpose to accommodate a type of gun (Rinella and Cambridge Batteries). In 1800 when the French capitulated the Sir Ralph Abercrombie compiled a list of the Ordnance found in Valletta. The cannonís calibre ranged from 36-pr to less than 3-pr. The majority however were 24-pr, 12-pr and 4-pr cannons. Lt. Col. W. Bentham was responsible for the first description of Ordnance and Carriages mounted around the Maltese Islands. In 1800, the British inherited a vast array of guns from the Knights. The most common guns were 24 pdr and many of them were expenisve bronze cannons which today are found on the front of important buildings such as Palaces or Churches. These guns continued to be used until the 1850s when Governor W. Reid became concerned that due to the various size there was the need of various projectile sizes. During the same period new Rifle Muzzle Loading Guns were developed. These became the standard armaments for the Fortifications built up to the 1890s. These guns came into various sizes the largest ever to be installed was the 17.25-inch 100-Ton guns. The Range of such guns amounted to a maximum of 7,000 yards. These guns were usually mounted en barbette however some were mounted on disappearing carriages or inside casemates. Breech Loading Guns were to replace RML guns by the 1890s as they proved more reliable and faster to re-load. However some RML guns were retained for the Saluting Battery or where converted into howitzers for the Howitzer Batteries near the Victoria Lines. The British decided to opt for 9.2 inch and 6 inch BL Guns for the defence of the Maltese Coast. These guns had an effective range of 15,000 yards, which is quite good for the defence of the Maltese coast. Prior to the 1st World War Quick Firing (QF) Guns were installed to counter any possibility of fast torpedo boat attacks. These guns had a shorter range than other Breech Loading Guns (around 10,000 yards). In the 1950 new dual-purpose guns were installed at Fort St. Rocco and Fort Benghisa but after a mere ten years in service these guns were dismantled. Other guns were cut and sold, as scrap and such was the fate of the 100-ton gun in Cambridge battery in Sliema.