page_title: Byzantine Empire
section_title: Second Arab Siege of Constantinople (717–718) and the Isaurian dynasty
hierarchical_section_title: Byzantine Empire / History / Shrinking borders / Second Arab Siege of Constantinople (717–718) and the Isaurian dynasty
caption_attribution_description: Leo III the Isaurian, with Constantine V, AV Solidus. Constantinople mint. d NO LEO-N PA MUL, crowned facing bust of Leo, holding globus cruciger &amp; akakia d N CONST-ANTINUM, crowned facing bust of Constantine, holding globus cruciger &amp; akakia.
context_page_description: The Byzantine Empire, also referred to as the Eastern Roman Empire, or Byzantium, was the continuation of the Roman Empire in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinople. It survived the fragmentation and fall of the Western Roman Empire in the 5th century AD and continued to exist for an additional thousand years until it fell to the Ottoman Empire in 1453. During most of its existence, the empire was the most powerful economic, cultural, and military force in Europe. "Byzantine Empire" is a term created after the end of the realm; its citizens continued to refer to their empire simply as the Roman Empire, or Romania, and to themselves as "Romans".
  Several signal events from the 4th to 6th centuries mark the period of transition during which the Roman Empire's Greek East and Latin West diverged. Constantine I reorganised the empire, made Constantinople the new capital and legalised Christianity. Under Theodosius I, Christianity became the state religion and other religious practices were proscribed.
context_section_description: In 717 the Umayyad Caliphate launched the Siege of Constantinople (717–718) which lasted for one year. However, the combination of Leo III the Isaurian's military genius, the Byzantines' use of Greek Fire, a cold winter in 717–718, and Byzantine diplomacy with the Khan Tervel of Bulgaria resulted in a Byzantine victory. After Leo III turned back the Muslim assault in 718, he addressed himself to the task of reorganising and consolidating the themes in Asia Minor. In 740 a major Byzantine victory took place at the Battle of Akroinon where the Byzantines destroyed the Umayyad army once again.
  Leo III the Isaurian's son and successor, Constantine V, won noteworthy victories in northern Syria and also thoroughly undermined Bulgarian strength. In 746, profiting by the unstable conditions in the Umayyad Caliphate, which was falling apart under Marwan II, Constantine V invaded Syria and captured Germanikeia and the Battle of Keramaia resulted in a major Byzantine naval victory over the Umayyad fleet. Coupled with military defeats on other fronts of the Caliphate and internal instability, Umayyad expansion came to an end.
caption: Gold solidus of Leo III (left), and his son and heir, Constantine V (right)
exif: {"Image ImageDescription": "", "Image Make": "NIKON", "Image Model": "E995", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS Windows", "Image DateTime": "2009:03:08 11:33:07", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "232", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "854", "Thumbnail JPEGInterchangeFormatLength": "0", "EXIF ExposureTime": "10/43", "EXIF FNumber": "101/10", "EXIF ExposureProgram": "Aperture Priority", "EXIF ISOSpeedRatings": "124", "EXIF ExifVersion": "0210", "EXIF DateTimeOriginal": "0000:00:00 00:00:00", "EXIF DateTimeDigitized": "0000:00:00 00:00:00", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ExposureBiasValue": "3/10", "EXIF MaxApertureValue": "0", "EXIF MeteringMode": "CenterWeightedAverage", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire", "EXIF FocalLength": "203/10", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "600", "EXIF ExifImageLength": "300", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "728", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed"}