Leo III the Isaurian
Emperor of the Eastern Roman Empire
"The city of the Virgin shall be the grave of the invader."
Biography
A soldier of humble origins from the eastern frontier, Leo III seized the imperial throne in 717 at the very moment the Umayyad Caliphate launched its greatest assault on Constantinople. In the year-long siege of 717–718 he masterminded one of the most important defensive victories in history — using the great walls, the terrifying Greek Fire that destroyed the Arab fleets, a Bulgar alliance that fell on the besiegers, and the miseries of a brutal winter to annihilate the vast Umayyad army and navy. The destruction of the invaders in 718 broke the momentum of the Islamic advance in the east and secured the survival of the Byzantine Empire — and, many historians argue, of Christian Europe. Leo went on to found a new dynasty and to launch the fierce controversy over icons known as Iconoclasm, but his enduring achievement was the salvation of Constantinople.
Did you know?
His victory in 718 is often bracketed with the Battle of Tours (732) as one of the two events that halted the Islamic expansion into Europe — though the siege was arguably the more decisive.
Key Battles
The Second Arab Siege of Constantinople
Byzantium, Persia & Their Neighbours victory717 – 718 · 60,000 total casualties
The catastrophic failure of the second siege in 718 was one of the most important battles in world history — often ranked with Tours as the event that saved Christian Europe from Islamic conquest. It broke the momentum of the Umayyad advance in the east and secured Byzantium's survival for centuries.
Life Journey
Timeline
c. 685
🌅 Birth
Born on the Syrian frontier
717–718
⚔️ Battle
Destroys the great Umayyad siege of Constantinople
June 18, 741
✝️ Death
Dies in Constantinople