Krum's campaigns Simeon I's campaigns Sviatoslav's invasion of Bulgaria Byzantine conquest of Bulgaria Uprising of Peter Delyan Second Bulgarian Empire The Battle of Ongal took place in the summer of 680 in the Ongal area, an unspecified location in and around the Danube Delta near the Peuce Island, present-day Tulcea County, Romania.

Batbayan, the eldest son, inherited the throne in Poltava but was defeated by and submitted to the rule of his ambitious relative Cozarig (Kotrag) who had undermined the state's unity by leading his Don-Volga "Kutrigs" in expansion campaigns extending his empire to the north where Volga Bulgaria would eventually form.

Eventually the Avars fought back and after Asparuh consolidated his rule they launched an attack against the Byzantine lands to the south.

In the meantime the Bulgar leader made an alliance with the Seven Slavic tribes for mutual protection against the Byzantines and formed a federation.

On seeing the multitude of cavalry and ships and amazed as they were by the unexpected suddenness (of the attack), the Bulgarians fled to their fortifications and remained four days there.

Now the emperor was seized by an attack of gout and being in much pain, sailed off to the city of Mesembria for treatment after giving orders to the officers and soldiers to keep on investing the fort and do whatever was necessary to oppose the nation.