Ruled between 715-717 AD, Theodosius III was a tax collector at Adramyttium (modern Edremit in the Aegean region) and became an imperial candidate by troops revolted against Anastasius II. He entered Constantinople (Istanbul) as an Emperor in 715 after a siege of six months, deposing Anastasius. He replaced the image of the Sixth Ecumenical Synod. In 716 he signed a treaty with the Bulgarians against Arab attacks on Constantinople, establishing the border in Thrace.In 717 AD, Leo III rebelled against Theodosius' rule and captured his son in Nicomedia (todays Kocaeli), so Theodosius chose to resign the throne. Along with his son, he subsequently entered the clergy and became bishop of Ephesus, where he's buried.