The Second Arab Siege of Constantinople is a combined land and sea effort by the Arabs to take the capital city of the Byzantine Empire, Constantinople.

The Arab ground forces, led by Maslama, are defeated by Constantinople's seemingly impregnable walls and Bulgarian attacks while their naval fleet is defeated by Greek Fire and the remnants of it subsequently sunk in a storm on its return home.

It is often compared to the more widely studied Battle of Tours in the fact that it halts Muslim expansion into Europe from the East for almost 700 years.