Bastion fort
Passive ring-shaped (Enceinte) fortifications of the Medieval era proved vulnerable to damage or destruction when attackers directed cannon fire on to perpendicular masonry wall.
Further structures, such as ravelins, tenailles, hornworks or crownworks, and even detached forts could be added to create complex outer works to further protect the main wall from artillery, and sometimes provide additional defensive positions.
[2] Bastion fortifications were further developed in the late fifteenth and early sixteenth centuries, primarily in response to the French invasion of the Italian peninsula.
Star forts were employed by Michelangelo in the defensive earthworks of Florence, and refined in the sixteenth century by Baldassare Peruzzi and Vincenzo Scamozzi.
The late-seventeenth-century architects Menno van Coehoorn and especially Vauban, Louis XIV's military engineer, are considered to have taken the form to its logical extreme.
When the newly-effective manoeuvrable siege cannon came into military strategy in the fifteenth century, the response from military engineers was to arrange for the walls to be embedded into ditches fronted by earthen slopes (glacis) so that they could not be attacked by destructive direct fire and to have the walls topped by earthen banks that absorbed and largely dissipated the energy of plunging fire.
Therefore, the shape was designed to make maximum use of enfilade (or flanking) fire against any attackers on the outer edge of the ditch and against any who should reach the base of any of the walls.
Defenders could move relatively safely in the cover of the ditch and could engage in active countermeasures to keep control of the glacis, the open slope that lay outside the ditch, by creating defensive earthworks to deny the enemy access to the glacis and thus to firing points that could bear directly onto the walls and by digging counter mines to intercept and disrupt attempts to mine the fort walls.
Fortifications of this type continued to be effective while the attackers were armed only with cannon, where the majority of the damage inflicted was caused by momentum from the impact of solid shot.
While purpose-built fortifications would often have a brick fascia because of the material's ability to absorb the shock of artillery fire, many improvised defences cut costs by leaving this stage out and instead opting for more earth.
Engineers from the 1520s were also building massive, gently sloping banks of earth called glacis in front of ditches so that the walls were almost totally hidden from horizontal artillery fire.
The first key instance of a trace Italianate was at the Papal port of Civitavecchia, where the original walls were lowered and thickened because the stone tended to shatter under bombardment.
With the original medieval fortifications beginning to crumble to French cannon fire, the Pisans constructed an earthen rampart behind the threatened sector.
Eventually it fell, but the Ottoman casualties were very high, and it bought time for the relief force which arrived from Sicily to relieve the rest of the besieged island.
[10][11] The Military Revolution thesis originally proposed by Michael Roberts in 1955, as he focused on Sweden (1560–1660) searching for major changes in the European way of war caused by the introduction of portable firearms.
Roberts linked military technology with larger historical consequences, arguing that innovations in tactics, drill and doctrine by the Dutch and Swedes (1560–1660), which maximized the utility of firearms, led to a need for more trained troops and thus for permanent forces (standing armies).
"Wars became a series of protracted sieges", Parker suggests, and open-pitch battles became "irrelevant" in regions where the trace Italienne existed.
Parker's emphasis on the fortification as the key element has attracted substantial criticism from some academics, such as John A. Lynn and M. S. Kingra, particularly with respect to the claimed causal link between the new fortress design and increases in army sizes during this period.
