Summary of the Evolution of Western Artillery Fortifications.
| Rough Dates | Main Weapons | Fortification | Generic Term |
| Phase 1 1440 to 1450 | Mainly forged iron guns, generally small in calibre. | High walls and round towers. | Post Medieval |
| Phase 2 1550 to 1850 | Cast smoothbore guns & standardisation. | Walls now protected by the moat with angular bastions. | Bastion Fortifications |
| Phase 3 1850 to 1900 | Rifled Muzzle Loader (RML) and later Breech Loading guns. | Multi facing fortifications with many aspects sunk below the ground for protection. | Polygonal |
| Phase 4 1900 to 1950 | High velocity Breech Loaders Bomber aircraft | Dispersed positions to suit the terrain. Barbed wire and anti-tank obstacles. Concrete bunkers and pillboxes. | Dispersed |
| Phase 5 1950 to Present | Rockets and air delivery of munitions. Mobile artillery. | Dispersed and hardened underground. | Nuclear |
The Unchanging Features of Fixed Defences
Offensive:
Weapons to engage enemy troops and vessels. This was primarily guns, smoothbore until about 1850 when rifled guns appeared in considerable numbers. Breach loading weapons also appeared about the same time and replaced the old smoothbores by 1900.
Defensive:
Protection for these guns, including bombproof or casemated positions, sometimes with armoured shields or turrets.
Prepared fields of fire and range finding equipment to ensure that they enemy could be hit.
Protection for the garrison, casemated and defensible barracks.
Obstacles to impede any enemy attack. In this case of naval vessels this including torpedoes (Brennan) either controlled or contact mines and boom defences.