Isaac II Angelos or Angelus (, ; September 1156 – January 1204) was Byzantine Emperor from 1185 to 1195, and again from 1203 to 1204. His father Andronikos Doukas Angelos was a military leader in Asia Minor (c. 1122 – aft. 1185) who married Euphrosyne Kastamonitissa (c. 1125 – aft. 1195). Andronikos Doukas Angelos was the son of Constantine Angelos and Theodora Komnene (b. 15 January 1096/1097), the youngest daughter of Emperor Alexios I Komnenos and Irene Doukaina. Thus Isaac was a member of the extended imperial clan of the Komnenoi. Rising by revolt Niketas Choniates described Isaac's physical appearance: "He had a ruddy complexion and red hair, was of average height and robust in body". During the brief reign of Andronikos I Komnenos, Isaac was involved (alongside his father and brothers) in the revolt of Nicaea and Prousa. Atypically, the Emperor did not punish him for this disloyalty, and Isaac remained at Constantinople. On 11 September 1185, while Andronikos was absent from the capital, his lieutenant Stephen Hagiochristophorites moved to arrest Isaac. Isaac killed Hagiochristophorites and took refuge in the church of Hagia Sophia. Andronikos was a capable ruler in some ways but was hated for his cruelty and his efforts to keep the aristocracy obedient. Isaac appealed to the populace, and a tumult arose that spread rapidly over the whole city. When Andronikos returned he found that he had lost popular support, and that Isaac had been proclaimed emperor. Andronikos attempted to flee by boat but was apprehended. Isaac handed him over to the people of the city, and he was killed on 12 September 1185. First reign Isaac II Angelos strengthened his position as emperor with dynastic marriages in 1185 and 1186. His niece Eudokia Angelina was married to Stefan, son of Stefan Nemanja of Serbia. Isaac's sister Theodora was married to the Italian marquis Conrad of Montferrat. In January 1186, Isaac himself married Margaret of Hungary (renamed Maria), daughter of King Béla III. Hungary was one of the Empire's largest and most powerful neighbours, and Margaret also had the benefit of high aristocratic descent, being related to the royal families of Kyiv, the Holy Roman Empire, Italy, Provence, and earlier Byzantine dynasties. Isaac inaugurated his reign with a decisive victory over the Norman King of Sicily, William II, at the Battle of Demetritzes on 7 November 1185. William had invaded the Balkans with 80,000 men and