Siege

For the Boston area punk band see Siege (band). For the James Mason book see Siege (book)

Sieges in the age of gunpowder

The introduction of gunpowder and the use of cannons brought about a new age in siege warfare. Cannons were first used in the early 13th century, but did not become significant weapons for another 150 years or so. By the 16th century, they were an essential and regularized part of any campaigning army, or castle's defences.

Related Topics:
Gunpowder - Cannon - 13th century - 16th century

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The greatest advantage of cannons over other siege weapons was the ability to fire a heavier projectile, further, faster and more often than previous weapons. Thus, 'old fashioned' walls—that is high and, relatively, thin—were excellent targets and, over time, easily demolished. In 1453, the great walls of Constantinople were broken through in just six weeks by the 62 cannon of Mehmet II's army.

Related Topics:
Constantinople - Mehmet II

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However, new fortifications, designed to withstand gunpowder weapons, were soon constructed throughout Europe. During the Renaissance and the Early Modern period, siege warfare continued to dominate the conduct of war in Europe.

Related Topics:
Renaissance - Early Modern

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Once siege guns were developed the techniques to assaulting a town or a fortress became well known and ritualised. The attacking army would surround a town. Then the town would be asked to surrender. If they did not comply the besieging army would surround the town with temporary fortifications to stop from the stronghold or relief getting in. The attackers would then build a length of trenches parallel to the defences and just out of range of the defending artillery. They would then dig a trench towards the town in a zigzag pattern so that it could not be enfiladed by defending fire. Once within artillery range another parallel trench would be dug with gun emplacements. If necessary using the first artillery fire for cover this process would be repeated until guns were close enough to be laid accurately to make a breach in the fortifications. So that the forlorn hope and support troops could get close enough to exploit the breach more zigzag trenches could be dug even closer to the walls with more parallel trenches to protect and conceal the attacking troops. After each step in the process the besiegers would ask the besieged to surrender. If after the forlorn hope stormed the breach successfully the defenders could expect no mercy.

Related Topics:
Zigzag - Enfilade - Forlorn hope

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Emerging theories on improving fortifications

The castles that in earlier years had been formidable obstacles were easily breached by the new weapons. For example, in Spain, the newly equipped army of Ferdinand and Isabella was able to conquer Moorish strongholds in Granada in 1482–92 that had held out for centuries before the invention of cannons.

Related Topics:
Ferdinand and Isabella - Moorish - Granada

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In the early 15th century, Italian architect Leon Battista Alberti wrote a treatise entitled De Re aedificatoria which theorized methods of building fortifications capable of withstanding the new guns. He proposed that walls be "built in uneven lines, like the teeth of a saw." He proposed star-shaped fortresses with low thick walls.

Related Topics:
15th century - Leon Battista Alberti

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However, few rulers paid any attention to his theories. A few towns in Italy began building in the new style late in the 1480s, but it was only with the French invasion of the Italian peninsula in 1494–95 that the new fortifications were built on a large scale. Charles VIII invaded Italy with an army of 18,000 men and a horse-drawn siege-train. As a result he could defeat virtually any city or state, no matter how well defended. In a panic, military strategy was completely rethought throughout the Italian states of the time, with a strong emphasis on the new fortifications that could withstand a modern siege.

Related Topics:
1480s - Charles VIII - Siege-train

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New styles of fortresses employed

The most effective way to protect walls against cannon fire proved to be depth (increasing the width of the defences) and angles (ensuring that attackers could only fire on walls at an oblique angle, not square on). Initially walls were lowered and backed, in front and behind, with earth. Towers were reformed into triangular bastions.

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This design matured into the trace italienne. Star-shaped fortresses surrounding towns and even cities with outlying defenses proved very difficult to capture, even for a well equipped army. Fortresses built in this style throughout the 16th century did not become fully obsolete until the 19th century, and were still in use throughout World War I (though modified for 20th century warfare).

Related Topics:
Trace italienne - 16th century - World War I

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However, the cost of building such vast modern fortifications was incredibly high, and was often too much for individual cities to undertake. Many were bankrupted in the process of building them; others, such as Siena, spent so much money on fortifications that they were unable to maintain their armies properly, and so lost their wars anyway. Nonetheless, innumerable large and impressive fortresses were built throughout northern Italy in the first decades of the 16th century to resist repeated French invasions that became known as the Wars of Italy. Many stand to this day.

Related Topics:
Siena - Wars of Italy

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In the 1530s and 1540s, the new style of fortification began to spread out of Italy into the rest of Europe, particularly to France, the Netherlands, and Spain. Italian engineers were in enormous demand throughout Europe, especially in war-torn areas such as the Netherlands, which became dotted by towns encircled in modern fortifications. For many years, defensive and offensive tactics were well balanced leading to protracted and costly wars such as Europe had never known, involving more and more planning and government involvement.

Related Topics:
1530s - 1540s - Netherlands

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The new fortresses ensured that war rarely extended beyond a series of sieges. Because the new fortresses could easily hold 10,000 men, an attacking army could not ignore a powerfully fortified position without serious risk of counterattack. As a result, virtually all towns had to be taken, and that was usually a long, drawn-out affair, potentially lasting from several months to years, while the members of the town were starved to death. Most battles in this period were between besieging armies and relief columns sent to rescue the besieged.

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Marshal Vauban

At the end of the 17th century, Marshal Vauban, a French military engineer, developed modern fortification to its pinnacle, refining siege warfare without fundamentally altering it: ditches would be dug; walls would be protected by glacis; and bastions would enfilade an attacker. He was also a master of planning sieges themselves. Before Vauban, sieges had been somewhat slapdash operations. Vauban refined besieging to a science with a methodical process that, if uninterrupted, would break even the strongest fortifications.

Related Topics:
17th century - Vauban - French - Glacis - Bastion - Enfilade

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Examples of Vauban-style fortresses in North America include Fort McHenry in Baltimore, Maryland, Fort Ticonderoga in New York State, and La Citadelle in Quebec City.

Related Topics:
North America - Fort McHenry - Baltimore, Maryland - Fort Ticonderoga - New York State - La Citadelle - Quebec City

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Planning and maintaining a siege is just as difficult as fending one off. A besieging army must be prepared to repel both sorties from the besieged area and also any attack that may try to relieve the defenders. It was thus usual to construct lines of trenches and defenses facing in both directions. The outermost lines, known as the lines of contravallation, would surround the entire besieging army and protect it from attackers. This would be the first construction effort of a besieging army, built soon after a fortress or city had been invested. A line of circumvallation would also be constructed, facing in towards the besieged area, to protect against sorties by the defenders and to prevent the besieged from escaping.

Related Topics:
Sortie - Contravallation - Circumvallation

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The next line, which Vauban usually placed at about 600 meters from the target, would contain the main batteries of heavy cannons so that they could hit the target without being vulnerable themselves. Once this line was established, work crews would move forward creating another line at 250 meters. This line contained smaller guns. The final line would be constructed only 30 to 60 meters from the fortress. This line would contain the mortars and would act as a staging area for attack parties once the walls were breached. It would also be from there that sappers working to undermine the fortress would operate.

Related Topics:
Mortars - Staging area

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The trenches connecting the various lines of the besiegers could not be built perpendicular to the walls of the fortress, as the defenders would have a clear line of fire along the whole trench. Thus, these lines (known as saps) needed to be sharply jagged.

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Another element of a fortress was the citadel. Usually a citadel was a "mini fortress" within the larger fortress, sometimes designed as a last bastion of defense, but more often as a means of protecting the garrison from potential revolt in the city. The citadel was used in wartime and peacetime to keep the residents of the city in line.

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As in ages past, most sieges were decided with very little fighting between the opposing armies. An attacker's army was poorly served incurring the high casualties that a direct assault on a fortress would entail. Usually they would wait until supplies inside the fortifications were exhausted or disease had weakened the defenders to the point that they were willing to surrender. At the same time, diseases, especially typhus were a constant danger to the encamped armies outside the fortress, and often forced a premature retreat. Sieges were often won by the army that lasted the longest.

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An important element of strategy for the besieging army was whether or not to allow the encamped city to surrender. Usually it was preferable to graciously allow a surrender, both to save on casualties, and to set an example for future defending cities. A city that was allowed to surrender with minimal loss of life was much better off than a city that held out for a long time and was brutally butchered at the end. Moreover, if an attacking army had a reputation of killing and pillaging regardless of a surrender, then other cities' defensive efforts would be redoubled.

Related Topics:
Strategy - Surrender

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Advent of mobile warfare

Siege warfare dominated in Western Europe for most of the seventeenth and eighteenth centuries. An entire campaign, or longer, could be used in a single siege (for example, Ostend in 1601–04; La Rochelle in 1627–28). This resulted in extremely elongated conflicts. The balance was that while siege warfare was extremely expensive and very slow, it was very successful—or, at least, more so than encounters in the field. Battles arose through clashes between besiegers and punative relieving armies, but the principle was a slow grinding victory by the greater economic power. The relatively rare attempts at forcing pitched battles (Gustavus Adolphus in 1630; the French against the Dutch in 1672 or 1688) were almost always expensive failures. Although during the English Civil War (1642–1651) there were many sieges the general maxim of the field armies was "Where is the enemy? Let us go and fight them. Or... if the enemy was coming... Why, what should be done! Draw out into the fields and fight them." {{ref|Defoe}} This was very different from the siege of Nuremberg during the 30 Years' War and was demonstated to the contenental powers by regiments of the New Model Army at the Battle of the Dunes (1658) during the Anglo-Spanish War.

Related Topics:
Seventeenth - Eighteenth - Ostend - La Rochelle - Gustavus Adolphus - 1630 - 1672 - 1688 - English Civil War - 1642 - 1651 - Siege of Nuremberg - 30 Years' War - New Model Army - Battle of the Dunes (1658) - Anglo-Spanish War

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However, this pattern was eradicated by the French Revolutionary and Napoleonic Wars. New techniques stressed rapidly moving armies that would clash on the open field of battle, and one single fortified stronghold was no longer as decisive as it used to be. Advances in artillery made previously impregnable defenses useless. For example, the walls of Vienna that had held off the Turks in the mid-seventeenth century were no obstacle to Napoleon in the late eighteenth. Where sieges occurred, the attackers were usually able to defeat the defences within a matter of days or weeks, rather than weeks or months as previously. But Lines of Torres Vedras (1810–1811), which were built by the Portuguese under the direction of Royal Engineers of the British Army during the Peninsular war were able to stop a French Army and were the first example of Trench warfare. The Siege of Sevastopol (1854–1855) during the Crimean War and those of Petersburg (1864–1865) during the American Civil War showed that modern citadels could still resist an enemy for many months. This era of rapidly moving armies continued through the 19th century. For example, the great Swedish white-elephant fortress of Karlsborg was built in the tradition of Vauban and intended as a reserve capital for Sweden, but it was obsolete before it was completed in 1869.

Related Topics:
French Revolutionary - Napoleonic Wars - Vienna - Turks - Napoleon - Lines of Torres Vedras - 1810 - 1811 - Royal Engineers - British Army - Peninsular war - Trench warfare - Siege of Sevastopol - 1854 - 1855 - Crimean War - Petersburg - 1864 - 1865 - American Civil War - 19th century - Karlsborg - 1869

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Advances in firearms technology without the necessary advances in battlefield communications gradually led to the defence again gaining the ascendacy. During the Franco-Prussian War, the battlefield front-lines moved rapidly through France. However, the Siege of Metz and the Siege of Paris held up German armies for months at a time due to the superior firepower of the Chassepot rifle and the principle of detached or semi-detached forts with heavy-caliber artillery. This resulted in the construction of fortress works across Europe such as the massive fortifications at Verdun.

Related Topics:
Franco-Prussian War - Siege of Metz - Siege of Paris - Chassepot - Artillery - Verdun

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