AD 727

By place

Byzantine Empire

• A revolt breaks out in Greece against the religious policies of Emperor Leo III. A rebel fleet under Agallianos Kontoskeles sets out for Constantinople with Kosmas, an anti-emperor, but is destroyed by the Byzantine fleet through the use of Greek fire.
• Siege of Nicaea: Muslim forces under Mu'awiya ibn Hisham penetrate deep into Asia Minor, and sack the fortress city of Gangra, but unsuccessfully lay siege to Nicaea.

  Europe

• A revolt breaks out in Italy against Leo's Iconoclasm; this results in the independence of the Exarchate of Ravenna, after part of a Byzantine invasion force is lost in a storm in the Adriatic Sea, and the remainder of Byzantine troops are repulsed.
• King Liutprand takes advantage of the anti-imperial turmoil. He conquers Bologna and other cities beyond the Po River. The Lombards take "Classis", the strategic seaport of Ravenna, and overrun the Pentapolis.

  Asia

• Arab–Khazar War: The Khazars drive back the Muslim invasion, led by Maslama ibn Abd al-Malik, into Mesopotamia. Reinforced with Syrian troops, Maslama counterattacks and takes Georgia, establishing the northern frontier on the Caucasus.

  By topic

Religion

• July - Pope Gregory II condemns iconoclasm at Rome, causing Italy to break with the Byzantine Empire. He becomes the virtual temporal ruler of most Byzantine possessions.