The Byzantine Empire experienced cycles of growth and decay over the course of nearly a thousand years. After the fall of the Western Roman Empire to Germanic invaders, the emperor Justinian I pursued an ambitious policy of reconquest, resulting in the restoration of Roman rule over much of the Mediterranean, although Britain, Gaul and much of the Iberian Peninsula and North Africa were lost forever. However, he began to be met with a number of crises towards the end of his reign, including conflict with the Sasanian Empire and a major plaque. His successors were increasingly forced onto the defensive, first against the Sasanians and later against the Islamic expansion, which resulted in the loss of the Levant, Egypt and Africa during the 7th century. At the same time, the Roman Empire lost control over much of Italy to the Lombards, while Slavic peoples settled the Balkans as far south as the Peloponnese and the Avars conducted raids deep into Byzantine territory, which effectively reduced Byzantine control in the Balkans to the coastal areas. In the aftermath, the empire found itself in a near-constant struggle for survival on multiple fronts, with frequent setbacks suffered especially against the Muslim Caliphates and the newly established First Bulgarian Empire, the latter of which conquered much of the remaining possessions on the Balkans from the empire during the 9th and 10th centuries.
During the Macedonian period, however, the Byzantine Empire saw a renewed territorial expansion, culminating with the conquest of Bulgaria under the reign of Basil II. Toward the end of the 11th century, however, the empire experienced a catastrophic loss of its heartland territories in Anatolia to the Seljuks following the Battle of Manzikert in 1071 and the ensuing civil war, leading to a migration of Turkic peoples into Anatolia. At the same time, the empire lost its last territory in Italy to the Norman Kingdom of Sicily, and faced repeated attacks on its territory in the Balkans. These events created the context for Emperor Alexios I Komnenos to call to the West for help, which led to the First Crusade and a partial recovery of Anatolia. Alexios and his successors John II and Manuel I Komnenos campaigned successfully in Anatolia and the Balkans, restoring much of the empire's power and prestige. However, the following turmoil and ensuing tensions with the West led to the Sack of Constantinople by the forces of the Fourth Crusade in 1204 and the dismemberment of the empire.
Although a number of small Byzantine successor states survived, one of which eventually reclaimed Constantinople in 1261, the empire had been severely weakened. Under the Palaiologoi, the empire was faced with near constant warfare with the Bulgarian and Serbian Empires, coupled with internal instability, frequent civil wars, and financial difficulties due to trade concessions to the Italian Republics of Venice and Genoa. This led to a growing negligence of the Anatolian frontier, and a gradual loss of territory to the Anatolian Beyliks, most prominently to the Ottomans. The early history of the eventual rise of Ottoman power remains shrouded in obscurity. One Byzantine chronicle refers to a skirmish between "Othman" and Byzantine forces in 1302 in the Marmara region near present day Yalova. By the early 1330s the Ottomans had taken Prusa (Bursa), Nicaea (Iznik), and Nicomedia (Izmit), while the last Byzantine city in Anatolia was taken in 1390.
Constantinople was left isolated as the Islamic empire gained a foothold in the Balkans under the leadership of Orhan Gazi and his son Murad I. They rapidly conquered the Byzantine European heartland over the course of the 14th century, leading to the Fall of Constantinople and the Fall of Trebizond by the army of Sultan Mehmed the Conqueror in the 15th century. Despite continued internal struggles between the Ottomans and the other Turkish rulers in Anatolia, Ottomans managed to conquer Despotate of Morea and Trebizond, the last truly Roman vestiges in Peloponnese and Anatolia respectively. The Ottomans thereafter mostly ignored the conflicts at home to focus on westward expansion into the Christian lands of southeastern Europe.
Timeline of decline
The most significant events generally agreed by historians to have played a role in the decline of the Byzantine Empire are summarised below:
The Battle of Manzikert in 1071, which saw emperor Romanos IV Diogenes captured by the army of Seljuk Sultan Alp Arslan. The defeat led to a Byzantine civil war lasting ten years, in which eight different revolts took place. The damage was increased by the use of Turkish mercenaries by the various factions, which in some cases led to Turkish occupation of entire cities and regions. A notable example is the revolt of Nikephoros Melissenos in 1080, in which the towns he had occupied and garrisoned with Turkish soldiers in Ionia, Phrygia, Galatia, and Bithynia remained in their hands even after the revolt ended, including Nicaea, which for a time became the capital of the Seljuk Sultanate of Rum. The Battle of Myriokephalon in 1176, in which an army led by emperor Manuel I Komnenos attempted to capture the Seljuk capital at Konya, but was ambushed in a narrow mountain pass and defeated by the army of Sultan Kilij Arslan II. The battle is generally considered significant both because it put an end to Byzantine plans to recover central Anatolia, and because of the psychological effect it had both on the emperor himself, and the empire's international reputation. In the years after Manuel's death in 1180, the Seljuks built on their victory by expanding their control at the expense of the Byzantines, while Manuel's teenage successor Alexios II was overthrown in a coup. The Sack of Constantinople in 1204 saw the weakened empire partitioned between the Republic of Venice and a Crusader army led by Boniface I, Marquess of Montferrat. A new Latin Empire was established, led by Baldwin I, Latin Emperor. Although Byzantine successor states emerged in Nicaea, Trebizond and Epirus, and went on to reclaim the capital in 1261, many historians cite the loss of the capital as a fatal blow to the Byzantine Empire. Furthermore, Latin Empire claimants continued to harass the Byzantine Empire in the hundred years following the 1261 reconquest. The Byzantine civil wars of the 14th century, including the Byzantine civil war of 1321–1328 and the Byzantine civil war of 1341–1347, caused unnecessary infighting which delayed the empire from responding to its nearby powerful neighbors and further destabilized the empire. The Fall of Gallipoli in 1354 saw the Ottoman Turks cross into Europe, while the empire was powerless to stop them. This event has been seen by modern historians such as Donald M. Nicol to be the point of no return for the Byzantine Empire, after which its fall was virtually inevitable.
Causes of the decline
Political Instability
Civil wars The period from 1071 to 1081 saw eight revolts:
1071–1072: The civil war between Romanos IV Diogenes and Andronikos Doukas. 1072: Uprising of Georgi Voiteh 1073–1074: Revolt of Roussel de Bailleul proclaims Caesar John Doukas Emperor. 1077–1078: Revolt and successful usurpation by Nikephoros III Botaneiates. 1077–1078: Revolt of Nikephoros Bryennios the Elder against Michael VII Doukas and Nikephoros III, defeated at the Battle of Kalavrye. 1078: Revolt of Philaretos Brachamios against Michael VII Doukas. 1078: Revolt of Nikephoros Basilakes against Nikephoros III. 1080–1081: Revolt of Nikephoros Melissenos against Nikephoros III. 1081: Revolt and successful usurpation by Alexios I Komnenos.
This was followed by a period of secure dynastic rule by the Komnenos dynasty, under Alexios I (1081–1118), John II Komnenos (1118–43) and Manuel I Komnenos (1143–1180). Cumulatively, these three emperors were able to partially restore the empire's fortunes, but they were never able to fully undo the damage caused by the instability at the end of the 11th century, nor return the empire's frontiers to those prior of 1071.
The second period of civil war and collapse took place after Manuel's death in 1180. Manuel's son, Alexios II Komnenos was overthrown in 1183 by Andronikos I Komnenos, whose reign of terror destabilised the empire internally and led to his overthrow and death in Constantinople in 1185. The Angelos dynasty which ruled Byzantium from 1185 to 1204 has been considered one of the most unsuccessful and ineffectual administrations in the empire's history. During this period, Bulgaria and Serbia broke away from the empire, further land was lost to the Seljuk Turks. In 1203, the imprisoned former emperor Alexios IV Angelos escaped jail and fled to the West, where he promised the leaders of the Fourth Crusade generous payment if they would help him regain the throne. These promises later proved to be impossible to keep; in the event, the dynastic squabbling between the weak and ineffectual members of the Angelid dynasty brought about the Sack of Constantinople; Constantinople was burned, pillaged and destroyed, thousands of its citizens were killed, many of the surviving inhabitants fled, and much of the city became a depopulated ruin. The damage to Byzantium was incalculable; many historians point to this moment as a fatal blow in the empire's history. Although the empire was reformed in 1261 by the recapture of the city by forces from the Empire of Nicaea, the damage was never reversed and the empire never returned to anywhere near its former territorial extent, wealth and military power.
The third period of civil war took place in the 14th century. Two separate periods of civil war, again making extensive use of Turkish, Serbian and even Catalan troops, often operating independently under their own commanders, and often raiding and destroying Byzantine lands in the process, ruined the domestic economy and left the state virtually powerless and overrun by its enemies. Conflicts between Andronikos II and Andronikos III, and then later between John VI Kantakouzenos and John V Palaiologos, marked the final ruin of Byzantium. The Byzantine civil war of 1321–1328 allowed the Turks to make notable gains in Anatolia and set up their capital in Prusa 100 kilometers from Constantinople. The civil war of 1341–1347 saw exploitation of the Byzantine Empire by the Serbs, whose ruler took advantage of the chaos to proclaim himself emperor of the Serbs and Greeks. The Serbian king Stefan Uroš IV Dušan made significant territorial gains in Byzantine Macedonia in 1345 and conquered large swathes of Thessaly and Epirus in 1348.Robert Browning, The Byzantine Empire (Washington D. C. :The Catholic U of America P, 1992), 240. In order to secure his authority during the civil war, Kantakouzenos hired Turkish mercenaries. Although these mercenaries were of some use to the Empire, by the time of Byzantine civil war of 1352–1357, Byzantines no longer had any control over them. In 1354 they seized Gallipoli after Tzympe from the Byzantines.Robert Browning, The Byzantine Empire (Washington D. C. :The Catholic U of America P, 1992), 241. By 1354, the empire's territory consisted only of city of Constantinople and Thrace, the city of Thessalonica, and some territory in the Morea. “At that time,” writes Nicephorus Gregoras, “the inhabitants of Constaninople, as well as the population of most of the Byzantine towns of Thrace, suffered from a lack of victuals. While civil war was exhausting Byzantium, the Turks conducted frequent naval incursions from Asia with the help of monemes and triremes galley ships, making their way with impunity into Thrace, especially during harvest season, seizing livestock, carrying off women and children into slavery, and causing such evils that these regions afterward remained depopulated and uncultivated. That was one of the reasons for the famine that the Byzantines had to endure.”
Loss of control over revenue