Investment (military)

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Reconstructed section of the investment fortifications at Alesia AlesiaFortifications.JPG
Reconstructed section of the investment fortifications at Alesia

Investment is the military process of surrounding an enemy fort (or town) with armed forces to prevent entry or escape. [1] [2] It serves both to cut communications with the outside world, and to prevent supplies and reinforcements from being introduced.

Town settlement that is bigger than a village but smaller than a city

A town is a human settlement. Towns are generally larger than villages but smaller than cities, though the criteria to distinguish them vary considerably between different parts of the world.


A circumvallation is a line of fortifications, built by the attackers around the besieged fortification facing towards an enemy fort (to protect the besiegers from sorties by its defenders and to enhance the blockade). [3] [4] The resulting fortifications are known as 'lines of circumvallation'. [5] Lines of circumvallation generally consist of earthen ramparts and entrenchments that encircle the besieged city. The line of circumvallation can be used as a base for launching assaults against the besieged city or for constructing further earthworks nearer to the city.

Siege military blockade of a city or fortress

A siege is a military blockade of a city, or fortress, with the intent of conquering by attrition, or a well-prepared assault. This derives from Latin: sedere, lit. 'to sit'. Siege warfare is a form of constant, low-intensity conflict characterized by one party holding a strong, static, defensive position. Consequently, an opportunity for negotiation between combatants is not uncommon, as proximity and fluctuating advantage can encourage diplomacy. The art of conducting and resisting sieges is called siege warfare, siegecraft, or poliorcetics.

A sortie is a deployment or dispatch of one military unit, be it an aircraft, ship, or troops, from a strongpoint. The sortie, whether by one or more aircraft or vessels, usually has a specific mission. The sortie rate is the number of sorties that a given unit can support in a given time. The term is an evolution of the concept of "sortie" in siege warfare.

Blockade effort to cut off supplies from a particular area by force

A blockade is an effort to cut off supplies, war material or communications from a particular area by force, either in part or totally. A blockade should not be confused with an embargo or sanctions, which are legal barriers to trade. It is also distinct from a siege in that a blockade is usually directed at an entire country or region, rather than a fortress or city. While most blockades historically took place at sea, blockade is still used on land to prevent someone coming into a certain area.

A contravallation may be constructed in cases where the besieging army is threatened by a field army allied to an enemy fort. [6] This is a second line of fortifications outside the circumvallation, facing away from an enemy fort. The contravallation protects the besiegers from attacks by allies of the city's defenders and enhances the blockade of an enemy fort by making it more difficult to smuggle in supplies. [7]



Schematic view of the circumvallation during the Siege of Groenlo in 1627 Siege of Grol (Groenlo) 1627 - Grolla Obsessa et Expugnata (J.Blaeu).jpg
Schematic view of the circumvallation during the Siege of Groenlo in 1627

Thucydides notes the role circumvallation played in the Sicilian Expedition and in the Spartan siege of Plataea during the initial stages of the Peloponnesian War in 429 BC.

Thucydides Greek historian and Athenian general

Thucydides was an Athenian historian and general. His History of the Peloponnesian War recounts the fifth-century BC war between Sparta and Athens until the year 411 BC. Thucydides has been dubbed the father of "scientific history" by those who accept his claims to have applied strict standards of impartiality and evidence-gathering and analysis of cause and effect, without reference to intervention by the deities, as outlined in his introduction to his work.

Sicilian Expedition Athenian military expedition to Sicily, which took place during the Peloponnesian War (415 BC to 413 BC).

The Sicilian Expedition was an Athenian military expedition to Sicily, which took place 415–413 BC during the Peloponnesian War between the Athenian empire on one side and Sparta, Syracuse and Corinth on the other. The expedition ended in a devastating defeat of the Athenian forces.

Plataea ancient city, located in Greece in southeastern Boeotia

Plataea or Plataia, also Plataeae or Plataiai, was an ancient city, located in Greece in southeastern Boeotia, south of Thebes. It was the location of the Battle of Plataea in 479 BC, in which an alliance of Greek city-states defeated the Persians.

Julius Caesar in his Commentaries on the Gallic War describes his textbook use of the circumvallation and contravallation to defeat the Gauls under their chieftain Vercingetorix at the Siege of Alesia in September 52 BC.

Julius Caesar 1st-century BC Roman politician and general

Gaius Julius Caesar, known by his nomen and cognomen Julius Caesar, was a populist Roman dictator, politician, military general, and historian who played a critical role in the events that led to the demise of the Roman Republic and the rise of the Roman Empire. He also wrote Latin prose.

Gaul region of ancient Europe

Gaul was a historical region of Western Europe during the Iron Age that was inhabited by Celtic tribes, encompassing present day France, Luxembourg, Belgium, most of Switzerland, and parts of Northern Italy, Netherlands, and Germany, particularly the west bank of the Rhine. It covered an area of 494,000 km2 (191,000 sq mi). According to the testimony of Julius Caesar, Gaul was divided into three parts: Gallia Celtica, Belgica, and Aquitania. Archaeologically, the Gauls were bearers of the La Tène culture, which extended across all of Gaul, as well as east to Raetia, Noricum, Pannonia, and southwestern Germania during the 5th to 1st centuries BC. During the 2nd and 1st centuries BC, Gaul fell under Roman rule: Gallia Cisalpina was conquered in 203 BC and Gallia Narbonensis in 123 BC. Gaul was invaded after 120 BC by the Cimbri and the Teutons, who were in turn defeated by the Romans by 103 BC. Julius Caesar finally subdued the remaining parts of Gaul in his campaigns of 58 to 51 BC.

Vercingetorix protohistoric chieftain of the Arverni tribe, defeated by Julius Caesar during the Gallic wars

Vercingetorix was a king and chieftain of the Arverni tribe; he united the Gauls in a revolt against Roman forces during the last phase of Julius Caesar's Gallic Wars.

Middle Ages

Another example from the pre-modern period is the siege of Constantinople in AD 717–718. The leaders of the Islamic Empire took advantage of the violent anarchy within the Byzantine state to prepare a huge host, comprising more than 100,000 troops and 1,800 ships, to take them to the capital Constantinople. Upon arriving outside the Theodosian walls, the Arab host had some knowledge that the Emperor Leo III the Isaurian had allied with Bulgaria under their khan Tervel, and so in preparation for the Bulgarian army, built a set of stone walls against the city and against the countryside, with the Arab camp in between. [8]

Constantinople capital city of the Eastern Roman or Byzantine Empire, the Latin and the Ottoman Empire

Constantinople was the capital city of the Roman Empire (330–395), of the Eastern Roman (Byzantine) Empire, of the brief Crusader state known as the Latin Empire (1204–1261) and of the Ottoman Empire (1453–1923). In 1923 the capital of Turkey, the successor state of the Ottoman Empire, was moved to Ankara and the name Constantinople was officially changed to Istanbul. The city is located in what is now the European side and the core of modern Istanbul. The city is still referred to as Constantinople in Greek-speaking sources.

Siege of Constantinople (717–718) combined land and sea offensive by the Arabs of the Umayyad Caliphate against the capital city of the Byzantine Empire, Constantinople

The Second Arab siege of Constantinople in 717–718 was a combined land and sea offensive by the Muslim Arabs of the Umayyad Caliphate against the capital city of the Byzantine Empire, Constantinople. The campaign marked the culmination of twenty years of attacks and progressive Arab occupation of the Byzantine borderlands, while Byzantine strength was sapped by prolonged internal turmoil. In 716, after years of preparations, the Arabs, led by Maslama ibn Abd al-Malik, invaded Byzantine Asia Minor. The Arabs initially hoped to exploit Byzantine civil strife and made common cause with the general Leo III the Isaurian, who had risen up against Emperor Theodosius III. Leo, however, tricked them and secured the Byzantine throne for himself.

Caliphate Islamic form of government

A caliphate is an Islamic state under the leadership of an Islamic steward with the title of caliph, a person considered a political-religious successor to the Islamic prophet Muhammad and a leader of the entire ummah. Historically, the caliphates were polities based in Islam which developed into multi-ethnic trans-national empires. During the medieval period, three major caliphates succeeded each other: the Rashidun Caliphate (632–661), the Umayyad Caliphate (661–750) and the Abbasid Caliphate (750–1258). In the fourth major caliphate, the Ottoman Caliphate, the rulers of the Ottoman Empire claimed caliphal authority from 1517. During the history of Islam, a few other Muslim states, almost all hereditary monarchies, have claimed to be caliphates.

King Pepin the Short of Francia built a number of fortified camps during his Siege of Bourbon (761) to completely surround the town. [9] He built a complete set of lines of circumvallation and contravallation during the Siege of Bourges (762). [10]

Modern era

The basic objectives and tactics of a military investment have remained the same in the modern era. During the Second World War there were many sieges and many investments. One of the best known sieges of World War II, which demonstrated the tactical use of investment, was the siege of Stalingrad. During the first half of the siege the Germans were unable to fully encircle the city, so the Soviets were able to get men and supplies in across the Volga River. In the second half of the battle, the complete investment of Stalingrad by the Soviets (including air space which prevented the construction by the Germans of an adequately large airbridge) eventually forced the starving Germans inside the city to surrender.

In modern times, investments and sieges of cities are often combined with intensive shelling and air strikes.

See also


  1. invest Merriam-Webster
  2. "4. Milit. The surrounding or hemming in of a town or fort by a hostile force so as to cut off all communication with the outside; beleaguerment; blockade" (Oxford English Dictionary: investment, n. Second edition, 1989; online version December 2011. Entry/99052. Earlier version first published in New English Dictionary, 1900).
  3. Definition of circumvallation
  4. Oxford English Dictionary: circumvallation, n. Second edition, 1989; online version December 2011. Entry/33402. Earlier version first published in New English Dictionary, 1889.
  5. Lines of Circumvallation/Contravallation and Interior/Exterior lines of communication
  6. Definition of contravallation
  7. Oxford English Dictionary: contravallation, n. Second edition, 1989; online version December 2011. Entry/40491. Earlier version first published in New English Dictionary, 1893.
  8. Petersen 2013, pp. 703–708.
  9. Petersen 2013, p. 729.
  10. Petersen 2013, pp. 730–731.

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