Following a period of relative success and expansion under the Macedonian dynasty (c. 867–c. 1054), Byzantium experienced several decades of stagnation and decline, which culminated in a vast deterioration in the military, territorial, economic and political situation of the Byzantine Empire by the accession of Alexios I Komnenos in 1081.

The problems the empire faced were partially caused by the growing influence and power of the aristocracy, which weakened the empire's military structure by undermining the theme system that trained and administered its armies. The remnants of the once-formidable armed forces were allowed to decay, to the point where they were no longer capable of functioning as an army.

The simultaneous arrival of aggressive new enemies – Turks in the east and Normans in the west – was another contributory factor. In 1040, the Normans, originally landless mercenaries from northern parts of Europe in search of plunder, began attacking Byzantine strongholds in southern Italy. The Seljuk Turks conducted a series of damaging raids into Armenia and eastern Anatolia – the main recruiting ground for Byzantine armies. The Battle of Manzikert in 1071 would eventually result in the total loss of Byzantine Anatolia.