Year 626 (DCXXVI) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. The denomination 626 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Byzantine Empire Siege of Constantinople: A horde of Avars, consisting of about 80,000 men (including large contingents of Slavs, Bulgars, and other "barbarians"), attack the walls of Constantinople. A small Persian army arrives on the Bosphorus, on the Asiatic side. The Theodosian Walls are stormed with the most up-to-date siege equipment, in the form of traction trebuchets. The Avars also have mobile armoured shelters (medieval 'sows') and siege towers; the latter are covered in hides for fire protection. The defense of the capital (12,000 well-trained Byzantine troops) is in the hands of Patriarch Sergius I and Bonus (magister militum). July 31 – The Avars and Persian allies under Shahrbaraz launch an attack along the entire length of the Theodosian Walls (about 5.7 kilometres); the main effort is concentrated against the central section, particularly the low-lying mesoteichion. After a fierce infantry battle on the walls, the Byzantine army holds off many assaults on the city. Emperor Heraclius makes arrangements for a new army under his brother Theodore to operate against the Persians in western Anatolia, while he returns to his own army in Pontus. August 7 – In the waters of the Golden Horn, the Persian fleet is destroyed while ferrying reinforcements. The Avars, having suffered terrible losses, running short of food and supplies, burn their siege engines. They abandon the siege and retreat to the Balkan Peninsula. The Byzantines achieve a decisive victory at Blachernae, under the protection of the Church of the Virgin Mary. Byzantine–Persian War: Heraclius, his army reduced by campaigning to less than 30,000 men, is on the defensive in Pontus. Apparently he leaves a strong Byzantine garrison in Trapezus, and withdraws north-eastward along the Black Sea into Colchis, where he halts the Persians by aggressive defensive-offensive operations along the Phasis River. By attracting the Persian army under Shahin Vahmanzadegan in Anatolia, he provides Theodore with the opportunity to defeat them. By the end of the summer he threatens the communication of the Persians at Chalcedon (modern Turkey). Heraclius invites the Croats, a Slavic tribe living in Galicia, Silesia, and Bohemia, to settle in Illyricum.