Byzantine Empire

An empire under pressure from several directions

The Byzantine Empire was the eastern continuation of the Roman Empire, with its capital at Constantinople. Its emperor ruled an Orthodox Christian state. During the period leading up to the First Crusade, however, Christianity did not unite all its neighbours: the empire faced attacks from western Christian Normans as well as Turkish forces and northern nomadic peoples.

When Alexios I Komnenos became emperor in 1081, he inherited shrinking territory, political instability and financial difficulties. These problems reinforced one another. Defending the empire required money and reliable armies, while struggles for the throne distracted commanders from defending its frontiers.

Manzikert and the loss of territory in Asia Minor

In August 1071, Seljuk forces defeated a Byzantine army at the Battle of Manzikert and captured Emperor Romanos IV. Although Romanos was released, the defeat was followed by a struggle over who should rule the empire.

This political conflict helped turn a military defeat into a much wider crisis. Byzantine commanders left their posts in Asia Minor to pursue claims to power in Constantinople. Turkish forces exploited the resulting weakness and expanded into Byzantine territory. The loss of territory therefore cannot be explained by the battle alone: internal rivalry made it harder to resist further advances.

The Sultanate of Rum, a Turkish-ruled state in Asia Minor, established its capital at Nicaea, captured from the Byzantines in 1081. This placed a hostile power in territory that Alexios wanted to recover. The empire had lost control of substantial areas, rather than merely suffered an isolated battlefield defeat.

Norman attacks from the west

The Normans had already taken Byzantine possessions in southern Italy, including Bari in 1071. In 1081, Robert Guiscard and his son Bohemond attacked Byzantine territory across the Adriatic, advancing into Greece. Alexios now had to defend the western side of the empire while Turkish forces held territory in the east.

Military action alone was not enough. Alexios used diplomacy to create problems for Guiscard in Italy and secured naval assistance from Venice. Nevertheless, Bohemond continued campaigning in Macedonia and Thessaly.

The immediate Norman threat receded in 1085, when disease struck their army and Guiscard died. Alexios recovered the important port of Dyrrachium, and the Norman invasion collapsed. This was a significant improvement, but the struggle had consumed resources that could otherwise have supported the recovery of Asia Minor.

Pecheneg attacks on the northern frontier

The Pechenegs, a nomadic people, threatened the empire from the north. They crossed the Danube and attacked Thrace, the region approaching Constantinople. Their attacks intensified during the later 1080s, and in 1090 they threatened the capital itself. Constantinople’s strong walls helped prevent its capture.

Alexios again sought allies rather than relying entirely on his own forces. With support from the Cumans, another nomadic people, he decisively defeated the Pechenegs at the Battle of Lebounion on 29 April 1091. This reduced the northern threat and gave him greater freedom to address problems elsewhere.

Political insecurity and the cost of defence

Alexios had gained the throne through a revolt against his predecessor. Rival aristocratic families and potential challengers made securing his own position an important concern. He placed trusted relatives in powerful offices and used marriage alliances to bring leading families together. The emperor needed loyal commanders as well as capable ones.

He also struggled to pay the mercenaries employed in his armies. He raised taxes and used Church valuables to obtain money. These measures show how military pressure became an economic burden on the empire and its population.

Help from allies also came at a price. In 1082, Alexios granted Venetian merchants exemption from customs duties in return for naval assistance against the Normans. This helped meet an urgent military need, but meant sacrificing customs income. A solution to one pressure could therefore worsen another.

Why Alexios appealed to the West in 1095

By 1095, Alexios had stabilised the empire considerably: the Norman invasion had collapsed and the Pechenegs had been defeated. Yet Turkish control of much of Asia Minor remained unresolved.

In spring 1095, he appealed to the West for military assistance, including an appeal to Pope Urban II. His central purpose was to obtain troops to defeat Turkish opponents and recover lost Byzantine territory. The request was a calculated attempt to strengthen the empire, not simply a desperate response to simultaneous attacks on every frontier. It helped set the First Crusade in motion, although the campaign that emerged had broader goals than Alexios’ request.

Main pressures, c.1070–1095

• East — Seljuk Turks: Manzikert, 1071, followed by struggles for the throne and Turkish expansion into Asia Minor. Nicaea fell in 1081 and became the capital of the Sultanate of Rum.
• West — Normans: Bari lost in 1071; Robert Guiscard and Bohemond invaded in 1081. The invasion collapsed after Guiscard’s death in 1085.
• North — Pechenegs: attacks on Thrace threatened Constantinople. Alexios defeated them with Cuman help at Lebounion, 29 April 1091.

Pressures reinforced one another

• Political rivalry: struggles for power diverted commanders from frontier defence; Alexios relied on trusted relatives and alliances.
• Financial strain: armies and mercenaries required money; higher taxes and Church valuables helped fund defence.
• Costly assistance: Venetian naval help secured through 1082 trading privileges, including exemption from customs duties.

The appeal of 1095

Alexios I, emperor from 1081, had reduced the western and northern threats but still wanted to recover Asia Minor. In spring 1095, he sought western military help through Urban II.

Key distinction: recovering Byzantine territory was Alexios’ central aim; capturing Jerusalem became the crusaders’ wider objective.