Union troops digging a sap with a sap roller on Morris Island, 1863
In 1583, after the month-long siege of Godesberg, the attackers blew up part of the mountain, causing the walls to crumble. The 72 defenders still held out for 2 days against a force five times their size.
The Star-shaped Fort at Groningen, restored to its 1750 condition, is an example of the trace italienne

Sapping is a term used in siege operations. Any trench excavated under defensive musket or artillery fire that was intended to advance a besieging army's position in relation to the works of an attacked fortification was referred to as a sap. Saps of approach were excavated by brigades of trained soldiers, often called sappers, because they dug the saps, or specifically instructed troops of the line.

By using the sap, or trench, a siege force could move closer to the walls of a fortress, without exposing troops to direct fire from the defending force, called enfilade. Once the saps were close enough, miners were often brought in to dig tunnels under the walls in which they would place bombs or powder kegs. Using long fuses, they would ignite the explosives and the ensuing force would create a gap in the fortification's defenses.


The age of gunpowder

During Cologne War, in the Siege of Godesberg, even the large caliber cannons brought to bear on the fortress by the superior force of the Ferdinand of Bavaria had little impact on the fortress itself. The cannons were firing heavy shells, but the height of the fortress significantly reduced the power with which they could hit the walls. Although the fortress dated from the 14th century, its construction caused the cannonballs to "bounce" from the walls, having little impact. To breach the walls, Ferdinand ordered his soldiers to dig into the feldspar supporting the side of the mountain. Even when the powder was ignited and a substantial portion of the wall, the gate, and the inner walls were blown into the air, the defenders still held out for three days.[1]

Trace Italienne

Sapping became a necessary process after the development of the Italian style bastion, or trace Italienne, in defensive architecture that made siege warfare the modus operandi of military operations in the late medieval and first decades of the early modern period of warfare.[2] Fortresses boasting abutments with gentler angles were difficult to breach; cannonballs and mortar shells often had little impact on the walls, or impact that could be readily repaired after night fell. Towers no longer protruded at right angles from the wall; rather, they blended with the wall. These created a two-fold advantage. First, defenders in the towers had a field of fire of 280 degrees or more. This range of fire and the towers' positioning allowed them to fire upon the attackers' flank as they advanced, a deadly fire called enfilade. Consequently, a seco which range their cannons were less effective.[clarification needed][3]

16th century

It illustrates an incident when a mine exploded during the Mughal attack on the Rajput fortress of Chitor (Chittaurgarh) in north-west India in 1567, killing many of the besieging Mughal forces. In right side Mughal sappers are shown preparing covered paths to enable the army to approach the fortress, while their opponents fiercely defend themselves.

During the Dutch Revolt, the Spanish controlled Groningen and the road leading to the German states, called the Bourtange passage. William I of Orange decided to build a fortification there to secure the road, which the Spanish were using to bring men and equipment into the provinces. The fort was completed in 1593. The star fort, or trace italienne, had a support network of canals and lakes, used as moats for additional protection. These were also constructed in the design of stars, giving the defenders added security. At the time of its completion, the fort housed five garrisons. Soon after its construction, Spanish forces from Groningen unsuccessfully besieged it.[4]

American Civil War

In the American Civil War, troops advanced their sap under cover of a sap roller[5] or mantlet[6] by forming a parapet on the engaged side of the trench one gabion at a time and filling it with earth taken from the trench.

See also


  1. ^ (German) Ernst Weyden. Godesberg, das Siebengebirge, und ihre Umgebung. Bonn: T. Habicht Verlag, 1864, p. 43.
  2. ^ Charles Townshend (editor). The Oxford history of modern war. Oxford: Oxford University Press. 2000, p. 28.
  3. ^ Townshend, pp. 28-29.
  4. ^ An Universal history pg. 455 [1]
  5. ^
  6. ^

External links

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Look at other dictionaries:

  • Sapping — Sap Sap, v. t. [imp. & p. p. {Sapped}; p. pr. & vb. n. {Sapping}.] [F. saper (cf. Sp. zapar, It. zapare), fr. sape a sort of scythe, LL. sappa a sort of mattock.] 1. To subvert by digging or wearing away; to mine; to undermine; to destroy the… …   The Collaborative International Dictionary of English

  • sapping — sæp n. juice of a plant, fluid which circulates through a plant; essential body fluid (such as blood); vigor, health, vitality; fool, gullible person (Slang); deep tunnel or trench leading to an enemy s fort (Military) v. remove sap, drain sap;… …   English contemporary dictionary

  • sapping — noun Geography undercut by water or glacial action. → sap someone of …   English new terms dictionary

  • Sapping — ♦ Undermining, as of a castle wall. (Gies, Joseph and Francis. Life in a Medieval Castle, 226) Related terms: Mine …   Medieval glossary

  • SAPPING — …   Useful english dictionary

  • Groundwater sapping — Scientists believe that groundwater sapping created these gullies in Noachis Terra on Mars. NASA image …   Wikipedia

  • basal sapping —   the undercutting and retreat of a slope caused when erosion and/or weathering are concentrated at its base …   Geography glossary

  • valley — valleylike, adj. /val ee/, n., pl. valleys. 1. an elongated depression between uplands, hills, or mountains, esp. one following the course of a stream. 2. an extensive, more or less flat, and relatively low region drained by a great river system …   Universalium

  • Coprates quadrangle — The Coprates quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Coprates quadrangle is also referred to as MC 18 (Mars Chart 18).[1] The Coprates… …   Wikipedia

  • Mining (military) — Explosion of the mine beneath Hawthorn Ridge Redoubt on the Western Front during World War I (July 1 1916). Photo by Ernest Brooks Mining, landmining or undermining is a siege method which has been used since antiquity against a walled city,… …   Wikipedia

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