The First Crusade
The Greek Emperor at the time was Alexius Comnenus, one of the greatest of the Byzantine emperors. He was the founder of the Comneni dynasty, having come to power in the wake of the terrible defeat at Manzikert in 1071 and a period of civil war. It was Alexius who had saved some vestige of the Empire in Asia Minor. It was Alexius who had fought the Normans. And it was Alexius who had written a letter to the Bishop of Rome, asking that soldiers be sent to Constantinople to help in the fight against the Turks.
The Emperor was relatively secure by the time the First Crusade arrived at his doorstep. He had put the Empire back on a solid economic footing and could look forward with reasonable confidence to recovering portions of Asia Minor. He had a good army and was an adept diplomat. He understood the Turks and their rivalries.
Everything, in fact, seemed to be in place for the Emperor to turn at long last from the defensive to the offensive. The Frankish warriors being sent by the Pope would prove a welcome addition—loyal barbarians from the West.
He was in for a severe disappointment.