This is a list of the wars or external conflicts fought during the history of the Eastern Roman or Byzantine Empire (395–1453). For internal conflicts see the list of Byzantine revolts and civil wars.
For conflicts of the Ancient Roman Kingdom, Republic and Empire see the: List of Roman wars and battles. 5th century and earlier
421–422: Roman–Sasanian War of 421–422 440: Byzantine–Sasanian War of 440 with Sassanid Persia 447: Battle of the Utus 468: Battle of Cape Bon 492: Battle of Cotyaeum – The Byzantine army under John the Scythian defeated the Isaurians under Longinus of Cardala.
6th century
502–506: Anastasian War with Sassanid Persia. 526–532: Iberian War with Sassanid Persia. Justinian campaigns (533–555): The Eastern Roman emperor Justinian launched an ambitious reconquest of Italy, North Africa and parts of Spain. However, new invaders like the Avars, Lombards and Slavs, alongside a pandemic known as the Plague of Justinian and various volcanic winters ended his ambition of recuperate the West and consolidate the reconquest. 533–534: Vandalic War in Northern Africa. 534–548: Moorish Wars in Africa. 535–554: Gothic War in Dalmatia and Italy. 541–562: Lazic War with Sassanid Persia. 552–555: Byzantine intervention in the Visigoth civil war in Spain, formation of Spania province. 560s–578: War with the Romano-Moorish kingdom of Garmul. 568-626: Avar-Byzantine wars in the Balkans and Greece including the siege of Constantinople in 626. 568-750: Byzantine-Lombard Wars in northern Italy. 572–591: Byzantine–Sasanian War of 572–591 over the Caucasus. 589: Franco-Lombard-Byzantine conflict over the Po Valley. The war was stopped by breaching dam in Cucca. 582–602: Maurice's Balkan campaigns against the Avars and Slavs in the Balkans.
7th century
The Eastern Roman emperor Heraclius adopted the Greek language as official language in 610. Constantinople's territorial control shrunk to Greece and Anatolia, because of Persian, Avar and finally Arab invasions. Due to these changing circumstances, the reign of Heraclius is often regarded as the turning point from which historiography stops calling it the "Eastern Roman Empire", and starts speaking of the "Byzantine Empire". 602–628: Byzantine–Sasanian War of 602–628: last Roman/Byzantine–Persian/Sasanian war. 626: Avar–Sasanian siege of Constantinople. 633–642: Beginning of the early Muslim conquests. The Rashidun Caliphate conquered Syria (634–638) and Egypt (639–642). 645–656: Renewed war with the Caliphate, loss of Cyprus and most of Armenia. The Rashidun advance towards Constantinople halted following the outbreak of the First Fitna. 647–709: Umayyad conquest of North Africa. 668–678: Renewed attacks on the Byzantine Empire by Muawiyah II, leading to the First Arab Siege of Constantinople. Following its failure, a truce was agreed, providing for payment of tribute, men and horses to the Empire. 676–678: Siege of Thessalonica by the local Slavic tribes. 680–681: Constantine IV's campaign against the Bulgar khan Asparukh ends in defeat, forcing the Empire to recognize the establishment of the First Bulgarian Empire in Moesia. 686–688: Successful Byzantine offensive established Byzantine control over Armenia and Caucasian Iberia, followed by favourable peace agreement with the Umayyad Caliphate, in return for the withdrawal of the Mardaites into the Empire. 688–689: Balkan campaign of Justinian II secured the coast between Thrace and Macedonia. Many Slavs were captured and resettled in imperial territory. Over 30,000 were incorporated into the Byzantine army. 689: Justinian II leads his army into Syria when Abd al-Malik ibn Marwan stops the payment of tributes due to Mardaites raids. Approximately 12,000 Mardaites are deported to the Empire. Peace is re-established and tributes resumed. 692–718: Almost constant war with the Arabs in various fronts. The defeat at the Battle of Sebastopolis and internal instability led to the gradual loss of Armenia and Cilicia, and despite some successes by Emperor Heraclius, the Byzantines generally maintained a defensive stance against the annual Arab raids into Anatolia. Carthage fell in 697. Recovered soon after, it was again lost in 698, marking the end of Byzantine North Africa. From 712 on, the Arab raids penetrated ever deeper into Anatolia, with the final objective of mounting an assault on Constantinople itself. The repulsion of the Second Arab Siege of Constantinople (717–718) was a major Byzantine success. Consider to be one of history's most important battles, the victory halted Muslim advance into Southeastern Europe for centuries.
8th century 708: War with Bulgaria ends in defeat at Anchialus. 720–740 : Annual Arab raiding expeditions (ṣawā'if) against Byzantine Anatolia resume. Stiffening Byzantine resistance leads to the victory at Akroinon at 740. 741–752: Campaigns of Constantine V against the Arabs, who were embroiled in civil war, leading to the recovery of all of Armenia and Cyprus. 755–767: War with the Bulgars. Constantine V defeats the Bulgar khan Telets, leading to the conclusion of a favourable peace treaty in 767. 772–775: War with the Bulgars under Telerig, launched as a pre-emptive strike by Constantine V. 775–782: War with the Abbasids. After the death of Constantine V in 775, Arab raids resumed. After a series of defeats in 778/779 and a stalemate in 780 and another defeat in 781. The Abbasids launched another major invasion under Harun al-Rashid, which led to the conclusion of a truce in 782. 780–783: Raids by the Bulgars under Kardam, leading to an agreement of non-aggression in exchange for annual payments. 783: Expedition of Staurakios against the Sclaviniae of Greece. 791–792 and 796: Campaigns against the Bulgarians under Constantine VI end in defeat at the Battle of Marcellae. 797–798: Large-scale invasion by Harun al-Rashid leads to the resumption of annual payments to the Caliphate in return for peace.
9th century 803–809: War with the Abbasids, resulting from Nikephoros I's cessation of annual tribute payments. The Arabs under Harun al-Rashid achieved significant early successes, but the outbreak of a revolt in Khorasan facilitated a Byzantine counter-offensive in 807–809. A truce in 809 restored the territorial status quo. 806–814: War with the Frankish empire as the Carolingian Empire over control of the Italian Peninsula, Dalmatia and the Adriatic Sea, and also the Problem of two emperors. Ended with the Pax Nicephori in a Status quo ante bellum and Republic of Venice as Buffer state. 808–816: Wars with the Bulgars, beginning with the Bulgarian capture of Sofia. A large-scale retaliatory campaign ended in the disastrous battle of Pliska (811), following which Krum of Bulgaria raided Eastern Thrace and secured a major victory at Versinikia. Following his death in 814, Leo V the Armenian defeated the Bulgars at Mesembria and secured a 30-year peace. 820s: Muslim conquest of Crete. 827–902: Muslim conquest of Sicily. 830–841: War with the Abbasids, with large-scale invasions launched by caliphs al-Ma'mun and al-Mu'tasim. Despite a crushing defeat at the Battle of Dazimon and the sack of Amorium in 838, Emperor Theophilos was able to conclude a truce in 841 without territorial losses, although raids by the Muslim border emirates continued. 830s: Rus' raid in Paphlagonia. ca. 844–878: Wars with the Paulicians of Tephrike end with the destruction of the Paulician state and its incorporation into the Empire. 851–863: War with the Abbasids and their clients. Successful Byzantine raids in Syria, Mesopotamia and Egypt are checked by a series of Muslim invasions of Anatolia in 860. Another invasion in 863 sees the complete annihilation of the Muslim army at the Battle of Lalakaon. 860: Rus' raid against Constantinople. 852, 855–856: Short wars with Bulgaria, ending in the recovery of several cities in northern Thrace. 871–885: Campaigns led by Basil I in person against northern Mesopotamia (871–873) are followed by a series of expeditions against the Muslims in Sicily and Southern Italy. The final loss of Sicily could not be averted, but the Arabs are driven from Southern Italy and Dalmatia, laying the foundations of the Catepanate of Italy. 894–896/897: War with Bulgaria under Tsar Simeon erupts over trade rights. It ends with a Bulgarian victory after the Battle of Bulgarophygon. The Byzantines agree to pay tribute and restore the market for Bulgarian goods to Constantinople.
10th century 907: Rus' raid against Constantinople. 913–927: War with Bulgaria under Tsar Simeon. 926–944: Byzantine offensive in the East under John Kourkouas, fall of Melitene and Theodosiopolis. 941: Rus' raid against Constantinople. 948–962: Constant large-scale raids and counter-raids along the Byzantine-Arab border, chiefly against the Hamdanid dynasty Emir of Aleppo, Sayf al-Daula. 960–961: Huge amphibious expedition against the Emirate of Crete under Nikephoros Phokas, resulting in the recapture of the island. 964–965: Byzantine conquest of Cilicia 964–975: Sustained Byzantine offensive in the East, under Nikephoros II Phokas and John I Tzimiskes, leads to the conquest of Cilicia, Cyprus, much of western Armenia and northern Syria. Aleppo becomes an imperial vassal. 970–971: War against the Kievan Rus' in Bulgaria. 976–1018: War against Bulgaria led by the Cometopuli dynasty. 986: Battle of the Gates of Trajan major defeat of Basil II at the hands of Samuel of Bulgaria 992–999: War with the Fatimids over Aleppo. Initial Fatimid victories over Michael Bourtzes lead to the direct intervention of Basil II, who clears northern Syria of the Fatimids and secures a ten-year truce
11th century 1014: Battle of Kleidion decisive victory over the Bulgarians under Samuel. 1018: Byzantine conquest of Bulgaria. 1021-1022: Campaigns of Basil II against Georgia. 1024: Battle of Lemnos 1027: Pecheneg raid in the Balkans is defeated by Constantine Diogenes. 1030–1032: War against the Muslims in Syria. Emperor Romanos III is defeated, but George Maniakes captured Edessa. 1032–1036: Operations against renewed Muslim piratical raids. The Byzantine fleet, including a large Varangian contingent, is victorious. 1038–1043: Campaigns of George Maniakes in Sicily and Southern Italy, until his own revolt against Constantine IX. 1040–1189: Byzantine–Norman wars 1040–1041: Uprising of Peter Delyan in Bulgaria failed. 1042: Battle of Bar, Stefan Vojislav asserts his state's independence from Byzantium. 1043: Rus' attack against Constantinople. 1046–1047: Byzantine–Pecheneg War 1048: First confrontation between Byzantines and the Seljuk Turks results in an indecisive battle at Kapetron. 1049–1053: Pecheneg Revolt in Thrace. 1068-1071: Siege of Bari The Normans conquered Bari and put an end to the Catepanate of Italy. 1071: Battle of Mantzikert The Seljuk Turks defeated the Byzantines and began the invasion of Anatolia. 1071-1072: War with Hungary: Hungarians capture Belgrade and Sirmium 1078: Suleyman creates the Sultanate of Rum after conquering Nicaea. 1081–1085: War against the first Norman invasion of the Balkans. Early Byzantine defeat at Dyrrhachium (1081), but the successful defence of Thessaly and naval victories with Venetian aid led to the eventual abandonment of the invasion after the death of Robert Guiscard. 1081–1095: Seljuk campaigns in the Aegean: Tzachas of Smyrna launches fleets in the Aegean and seizes a number of islands, but is eventually defeated by the Byzantines. 1086–1091: Uprising of the Bogomils in the Balkans, aided by the Cumans and Pechenegs. Early Byzantine defeat at Dristra (1086), but the Pechenegs were decisively defeated at the Battle of Levounion in 1091. 1090–1095: Byzantine–Serbian War