The History of Byzantium

Alexios Angelos faces down one internal rebellion after another as the Roman Empire continues to contract. The biggest threat to his throne comes from disgruntled aristocrats and the people of Constantinople. 

Isaac Angelos does his best to secure his position and confront the Bulgarians. But he is overthrown by his brother at the head of a coalition of aristocratic families.

As soon as news reached the West that Jerusalem had fallen a new Crusade was called. The German, French and English Kings all led armies East but only Frederick Barbarossa went by land. He led a large army across the Balkans towards Constantinople and Isaac Angelos had to decided whether to treat him as friend or foe.