Sieges and Siege Techniques: Modern Summary

  • Last updated on November 11, 2022

A siege is an operational method used by armies to capture heavily fortified or defended areas, including cities and castles.

Nature and Use

A siege is an operational method used by armies to capture heavily fortified or defended areas, including cities and castles. The process begins when the besieging force cuts off access and egress to the besieged area. The purpose of this action is to prevent resupply or reinforcement of or escape from the garrison, compelling the garrison to surrender with minimal loss to the attacking force. If the besieged force does not surrender once it is surrounded, the siege continues until the attacker gives up or storms the fortifications using its military capabilities. Against a determined defense, the latter option could result in significant casualties to one or both sides.Siege warfare;modernSiege warfare;modern


In the early modern period, siege warfare closely resembled siege warfare of the earliest recorded times. In general, once the line of Circumvallationcircumvallation, or wall that denied the besieged city any outside contact, was completed, the opposing forces sat and waited for one side or the other to run out of supplies. The ability to create a breach in the defenses was extremely limited, and going over the defenses was extremely costly in lives.

Cannons were used by the English during the Siege of Calais (1346-1347). The Cannons;siege warfarecannons of the day were direct-fire weapons with limited range and power. It was not until the Siege of Constantinople Constantinople, Siege of (1453)[Constantinople, Siege of 1453](1453) that a Mortars;siege warfaremortar was able to lob artillery fire over the walls and into the defenses behind them. Although these new weapons made it a little easier to breach some defenses, they did not alter the way sieges were conducted. It was not until Charles Charles VIIICharles VIII (king of France)[Charles 08]VIII (1470-1498) of France invaded Italy in Italy;French invasion of 14941494, with what is considered the first modern artillery Artillery;trainstrain, that artillery became a significant part of siege warfare. The first major impact of this development was the change in the design of city and castle defenses from high, narrow walls to low, thick walls that were more resistant to artillery fire.

In the early part of the sixteenth century as the Turks expanded their Ottoman Empireempire throughout the Mediterranean, there were few forces standing in their way. By 1565 the only obstacle to complete Turkish domination of the region was the fortress of the Knights Knights Hospitaller;Malta fortressHospitallers on the island of MaltaMalta. This fortress was commanded by Jean Parisot La La Valette, Jean ParisotLa Valette, Jean Parisot[LaValette]Valette (1494-1568), whose strenuous defense, coupled with timely help from outside forces, prevented the Turks from seizing the fortress and blocked the westward expansion of the Ottoman Empire.

Gradually, over time, the art of Fortifications;modernfortification developed beyond the capacity of attacking forces to overcome. Many books were written on the subject, the first by the Italian Jacomo Castriotto, JacomoCastriotto, JacomoCastriotto (c. 1530-c. 1570) in 1564 and later by the Frenchman Blaise François, comte de Pagan, Blaise François, comte dePagan, Blaise François, comte dePagan (1604-1653) in 1541 and Chevalier Antoine de Ville, Antoine deVille, Antoine deVille (1596-1657) in 1625. However, no one took the time to write about capturing these great new fortifications. The weapons of the day were incapable of overcoming building technology, so sieges remained a waiting game.

The waiting game continued well into the seventeenth century. It was at Stenay Stenay, Siege of (1654)(1654) where a little known French Engineers;Frenchengineer, Sébastien Le Prestre de Vauban, Sébastien Le Prestre deVauban, Sébastien Le Prestre deVauban (1633-1707) first made his presence felt. Vauban succeeded in taking the fortress by siege, resulting in his becoming the king’s engineer. Over the next fifty years, Vauban would revolutionize the art of siege warfare. He became the greatest military engineer of his day and changed the way sieges would be fought for generations to come. In fact, his fortress at Maubeuge fortressMaubeuge would stand against German assaults for nearly two weeks in 1914. It was said that there was no fortification Vauban could not take and that no fortification built by Vauban would fall. Of course, there were several occasions on which Vauban was forced to lay siege to his own work.

In his lifetime Vauban constructed more than one hundred fortified locations and conducted dozens of sieges. During this period he made two major contributions to the art of siege warfare. At the Siege of Maastricht Maastricht, Siege of (1673)(1673), he first employed the system that became known as “saps and Saps and parallels systemparallels” to capture the city in thirteen days. The saps and parallels system would be the standard method for besieging fortresses for the next 160 years, culminating in the last of the great classical sieges, the Siege of Antwerp in Antwerp, Siege of (1831)1832.

Vauban’s system was simple and Engineers;Frenchelegant. Once the fortress or city was cut off, a trench was dug around the target. This trench, dug at long range for cannons of the day, was called the first parallel. Once the first Parallels (trenches)parallel was complete, a series of saps were dug toward the fortifications. These saps were also trenches, dug in a zigzag manner to prevent the defending force from getting a clean shot at the engineers doing the work. At approximately medium range for cannons, a second parallel that circled the enemy positions connected these saps. Along this second parallel, artillery positions were prepared, so that the attacker’s cannonfire could achieve better results.

Once the supporting troops were in place, another set of saps was dug toward the enemy positions. This second set of saps was connected by a third parallel, constructed at close range for the cannons. Again, the parallel would contain artillery positions. From the third parallel the final assault would be conducted. Vauban was able to develop the system to the point where he was able to predict the time until the successful completion of the siege before it even started. The entire process was codified in his book, De l’attaque et de la défense des places (1737-1742; attack and defense).

The second of Vauban’s innovations dealt with effective use of cannons during sieges. The cannons of the day were low-trajectory, direct-fire weapons that were used to batter away at the enemy defenses but which could do little else. It was during the Siege of Philippsburg Philippsburg, Siege of (1688)(1688-1697) that Vauban developed the concept of ricochet Ricochet firefire, making the cannons more useful. He determined a method that allowed the cannonball to bounce off the fortification walls and into the area behind it, causing damage and disruption to previously protected activities. Ricochet fire remained an artillery technique until the development of the howitzer in the 1830’s ended the need for it.

The seventeenth century would showcase a number of great Engineers;Dutchengineers who left their mark on siege warfare. After Vauban, perhaps the second most significant was the Dutch engineer Baron Menno vanCoehoorn, Menno vanCoehoorn, Menno vanCoehoorn (1641-1704). Coehoorn is known for two significant contributions to siege warfare. The first was his advocacy of the direct method of resolving sieges. He felt that one should look for shortcuts, trading lives for time if necessary, and that storming the defenses was preferable to starving the defenders. His second contribution was the Coehoorn mortar. Like other Mortars;Coehoornmortars, it had a short range and a high trajectory, useful for lobbing shells over walls. The major difference was that his mortar was designed to be lightweight and easily transportable and to lob small, antipersonnel grenades with a high rate of fire. The high rate of fire would keep the enemy pinned down while his forces could storm the works.

The fortifications constructed in the French, Dutch and, later, German styles, as developed by Vauban, Coehoorn, and others during the late seventeenth and early eighteenth centuries, changed the face of warfare in Europe for the next one hundred years. During the period from 1749 to 1815 a total of 289 major sieges were conducted throughout Europe, representing more than one-third of the total major engagements during the period. Even in North America sieges played a key role; the Siege of Yorktown Yorktown, Siege of (1781)(1781), for example, ended the American Revolution American Revolution (1775-1783)(1775-1783).

George Washington and the comte de Rochambeau at the Siege of Yorktown, which effectively ended the American Revolutionary War.

(North Wind Picture Archives via AP Images)

By the middle of the nineteenth century, the science of artillery had overtaken the science of fortifications. Advancements in gunpowder technology, forging, and projectile design changed the face of siege operations. New gunpowder mixes and better metallurgy increased the range of the weapons, and rifling and shell aerodynamics improved accuracy. It was no longer necessary to dig saps and parallels close to the defenses. They could be attacked more effectively, and safely, from longer ranges. The development of the howitzer made indirect fire much more effective as well. Expensive fixed fortifications became obsolete except at large cities.

As the role of permanent fortifications declined, the value of field, or temporary, fortifications increased. The field fortification of choice was the Trench warfaretrench. Most of the sieges over the later part of the nineteenth century involved rings of trenches on both sides, rather than those constructed by the attackers. In North America, key examples were the Sieges of Vicksburg Vicksburg, Siege of (1863)(1863) and Petersburg Petersburg, Siege of (1864-1865)(1864-1865), both during the American Civil War (1861-1865). In Europe, despite the presence of major permanent fortifications, the same was true. Both sides fought from trenches during the Siege of Paris Paris, Siege of (1870)(1870) during the Franco-Prussian War (1870-1871). This trend continued through the end of World War I. To some extent, combat across the entire western front of that war had devolved to siege warfare techniques by early 1915.

The introduction of the Tankstank to the battlefield late in World War I began the move away from trenches and toward Strongpointsstrongpoints. Defensive works soon became a series of individual strongpoints or fortifications, linked by fields of fire and communications lines but fighting independently. This change would also affect the way sieges were conducted. It was no longer possible to create one breach and force the defender to surrender; each strongpoint had to be dealt with individually. However, some fundamental rules still applied. The first objective of a besieging force remained the isolation of the defender from resupply and reinforcement. This was no longer done with lines of circumvallation, however, but with strongpoints and patrols. Once that had been accomplished, the attacker then sought to create weaknesses in the defense. Finally, if surrender was not obtained, storming was necessary.

Each of these steps became more difficult to make as technology advanced. As weapon lethality increased, so did troop dispersion. It became more difficult to concentrate forces to cut off the defender. Too many holes existed and small units could escape by avoiding the besieger’s patrols and fixed positions. Besiegers were further hindered by the increased use of aircraft for Aircraft;resupplyresupply. It was no longer necessary to move through the sieges. Instead, supplies and reinforcements could be brought in over the top of the lines. There were limitations, however, as the Germans found out during World War II at Stalingrad Stalingrad, Siege of (1942-1943)(1942-1943). The number of aircraft sorties required to resupply the army was beyond the capability of the German air force, and eventually the surviving 91,000 men of the German Sixth Army were forced to surrender to the Russians. Similarly, in Vietnam at Dien Bien Phu Dien Bien Phu (1954)(1954), the French attempted to supply their defending force by air. Although they were successful for some time, the attacking Vietnamese inflicted enough damage to the runway that flights in and out became impossible. The introduction of the helicopter diminished the need for runways and made aerial resupply more practical, but limited lift capacity was a problem. At Khe Sanh Khe Sanh (1968)(1968) American forces were able to successfully resupply their forces in this manner and were able to break the siege.

The introduction of the atom Atomic bombbomb (1945) and other weapons of mass destruction have provided a possible means to overcome any strongpoint but also present tremendous risk to the entire environment. Since the late 1960’s, advances in conventional weapons technology have also greatly reduced the need to conduct sieges. Precision strikes, remote imagery, and other tools make the work of assaulting defended positions so much easier that attacking armies in the most recent large-scale conflicts have not had to resort to sieges in order to clear enemy positions.Siege warfare;modern

Books and Articles
  • Bruce, Robert B., et al. “Artillery and Siege Warfare.” In Fighting Techniques of the Napoleonic Age, 1792-1815: Equipment, Combat Skills, and Tactics. New York: Thomas Dunne Books/St. Martin’s Press 2008.
  • Burke, James. “Siege Warfare in Seventeenth Century Ireland.” In Conquest and Resistance: War in Seventeenth-Century Ireland, edited by Pádraig Lenihan. Boston: Brill, 2001.
  • Duffy, Christopher. Siege Warfare: The Fortress in the Early Modern World, 1494-1660. 1979. Reprint. London: Routledge, 1996.
  • _______. Siege Warfare: The Fortress in the Age of Vauban and Frederick the Great, 1660-1789. London: Routledge and Kegan Paul, 1985.
  • Eltis, David. “The New Siege Warfare and Its Implications.” In The Military Revolution in the Sixteenth Century. London: I. B. Tauris, 1995.
  • Haskew, Michael E., et al. “Siege Warfare.” In Fighting Techniques of the Oriental World, A.D. 1200-1860: Equipment, Combat Skills, and Tactics. New York: Thomas Dunne Books/St. Martin’s Press, 2008.
  • Jörgensen, Christer, et al. “Siege Warfare.” In Fighting Techniques of the Early Modern World, A.D.1500-A.D.1763: Equipment, Combat Skills, and Tactics. Staplehurst, England: Spellmount, 2005.
  • Melegari, Vezio. The Great Military Sieges. London: New English Library, 1972.
  • Showalter, Dennis E., and William J. Astore. “Gunpowder Cannons, New Fortresses, and Siege Warfare.” In The Early Modern World. Westport, Conn.: Greenwood Press, 2007.
  • Watson, Bruce Allen. Sieges: A Comparative Study. Westport, Conn.: Praeger, 1993.
Films and Other Media
  • Masada. Television miniseries. Arnon Milchan Productions, 1981.
  • The Messenger: The Story of Joan of Arc. Feature film. Gaumont, 1999.
  • Soldiers: A History of Men in Battle, Engineer. Documentary. Churchill Films, 1990.
  • Yorktown. Documentary. Colonial Williamsburg Foundation, 2006.

Modern Fortifications

Categories: History