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Battle of Ad Decimum

The Battle of Ad Decimum took place on September 13, 533 between the armies of the Vandals, commanded by King Gelimer, and the Byzantine Empire, under the command of general Belisarius. This event and events in the following year are sometimes jointly referred to as the Battle of Carthage, one of several battles to bear that name. The Byzantine victory marked the beginning of the end for the Vandals and began the reconquest of the west under the Emperor Justinian I.

Battle of Ad Decimum
Part of the Vandalic War
DateSeptember 13, 533
Result Byzantine victory
Byzantine Empire Vandal Kingdom
Commanders and leaders
John the Armenian
18,000 men[1] or 15,000 men Greater than the Romans[2] or 10,000-12,000 men[1] or 11,000 men
Casualties and losses
Unknown Unknown


The Vandal Kingdom in North Africa was ruled by King Hilderic. His reign was noteworthy for the kingdom's excellent relations with the Byzantine Empire ruled by emperor Justinian I.[1] Procopius writes that he was "a very particular friend and guest-friend of Justinian, who had not yet come to the throne"[citation needed], noting that Hilderic and Justinian exchanged large presents of money to each other. Hilderic allowed a new Catholic bishop to take office in the Vandal capital of Carthage, and many Vandals began to convert to Catholicism, to the alarm of the Vandal nobility. Hilderic rejected the Arian Christianity that most Vandals followed. However, in 531,[3] Hilderic was overthrown by his cousin Gelimer, a popular military commander who had commanded successfully against the Moors.[1] Gelimer began persecuting non-Arian population, and many fled to the Byzantine Empire. Justinian sent Byzantine general Belisarius to reconquer the former Roman province of North Africa. On Midsummer Day 533 the expedition set off. It consisted of 5,000 Byzantine cavalry and twice as many infantry and some additional units but their number and composition is not named by the primary sources.[1] They travelled in a fleet of 500 transports,[1] escorted by ninety-two dromons.[4] Once the fleet arrived safely in North Africa, the Byzantine army disembarked and marched up the coast to Carthage, the Vandal capital, the ships keeping pace with the army offshore.[1] Contact with the fleet was lost however when it has to sail round Cape Bon.[1]


Ad Decimum (Latin for "at the tenth [mile post]"), was simply a marker along the Mediterranean coast 8 miles (13 km) (using modern miles) south of Carthage. When hearing of the Byzantine landing Gelimer marched from his position 4 days marching inland to the north towards Ad Decimum.[1] He divided his forces, sending 2,000 men under his nephew Gibamundus to block one of the three roads to Carthage, to other two converging at Ad Decimum.[1]

Gelimer retained 5,000-6,000 men under his own command while Ammatus, Gelimer's brother, was approaching from the north with 6,000-7,000, Ammatus himself travelling ahead to scout.[1] At Ad Decimum there was a narrow valley were the Byzantines could be trapped.[1] The Byzantines didn't know the layout of the road network and would probably be surprised if an army appeared behind them.[1] When the Byzantines advanced towards Carthage they would most likely try to go through the path blocked by Gibamundus who was ordered to charge them.[1] This was supposed to push the Byzantines back into the valley and disorganise them.[1] Gelimer would advance into the valley and attack them from behind.[1]

When Belisarius landed in North Africa he knew the Vandals would move against him before he could reach Carthage.[4] However he didn't know the Vandal dispositions so he wanted to gain intel on them before giving battle.[1][5][6] At the time when Ammatus was scouting the location of the battle Belisarius found a good spot for a fortified camp 4 miles, leaving his infantry there he advanced with his cavalry.[1][4] Belisarius hadn't ordered the 300 strong contingent of scouts, under John the Armenian, or the 600 Huns guarding his left flank to stop so they kept advancing while Belisarius was still with his encamping infantry.[1]


Gibamundus failed to accomplish his mission, as the 600 Hun mercenaries drove his 2,000-man force off and killed him.[1] Ammatas also failed, he arrived at the defile ahead of his army to scout, his men still strung out along the road back to Carthage, he was surprised upon seeing the more numerous Byzantine scouts he and was killed in the ensuing combat.[1] The Romans pursued his men all the way to the gates of Carthage itself.

Gelimer's main force, however, inflicted serious casualties on the Byzantine troops along the main road. The Byzantine mercenary cavalry was routed by the Vandals, and even though Gelimer was outnumbered, his men were performing well in the fighting. It appeared as though the Vandals would win the battle.

But when Gelimer reached Ammatas's position and discovered that his brother had been killed, by the vanguard of John the Armenian,[7] he became disconsolate and failed to give an order for one more assault — which would probably have destroyed the reeling Roman army and cut off the Huns and Byzantines who had earlier advanced toward Carthage after beating Ammatas and Gibamund. Instead, the Vandal attack was weakened while Gelimer buried his brother on the battlefield. [8]

Given a respite, Belisarius was able to regroup his forces south of Ad Decimum and launch a counterattack, which drove the Vandals back and soon routed them. Gelimer was forced to abandon Carthage.


Belisarius camped near the site of the battle, not wanting to be too close to the city at night. The next day he marched on the city, with his wife Antonina at his side, ordering his men not to kill or enslave the population (as was normal practice at the time) because he stated the people were actually Roman citizens under Vandal rule. They found the gates to the city open, and the army was generally welcomed. Belisarius went straight to the palace and sat on the throne of the Vandal King. He then set about rebuilding the fortifications of the city, and his fleet sought shelter in the Lake of Tunis, five miles (8 km) south of Carthage.

After a second defeat at the Battle of Tricamarum later in the year, the Vandal kingdom was all but ended.


  1. ^ a b c d e f g h i j k l m n o p q r s t u Hughes, Ian (Historian) (2009). Belisarius : the last Roman general. Yardley, Pa.: Westholme. ISBN 9781594160851. OCLC 294885267.
  2. ^ Anthony Brogna (1995), the Generalship of Belisarius
  3. ^ J-J.Norwich "A short history of Byzantium", Penguin Books-
  4. ^ a b c Brogna, Anthony (2015). The Generalship of Belisarius. Hauraki Publishing.
  5. ^ "History of the Wars/Book III - Wikisource, the free online library". Retrieved 2019-11-28.
  6. ^ Procopius; Dewing, H. B. (Henry Bronson) (1914). Procopius, with an English translation by H.B. Dewing. Robarts - University of Toronto. London S. Heinemann.
  7. ^ Procopius 2005, p. 9.
  8. ^ Beck 2004, p. 1.


Further readingEdit

Coordinates: 36°45′00″N 10°20′00″E / 36.7500°N 10.3333°E / 36.7500; 10.3333