The Empire, as the largest, richest and…

The Empire, as the largest, richest and militarily strongest state bordering the expanding Caliphate, has been the Muslims' primary enemy, aince the beginning of the Muslim conquests.

Following the disastrous Battle of Sebastopolis in 692, the imperial armies have largely confined themselves to a defensive strategy, while the Muslim armies regularly launch raids into imperially held Anatolia.

Following their failure to capture the imperial capital, Constantinople, in 717–718, the Umayyads for a time had diverted their attention elsewhere.

From 720/721, however, they had resumed these expeditions in a regular pattern: each summer one or two campaigns have been launched, sometimes accompanied by a naval attack and/or followed by winter expeditions.

These are no longer aimed at permanent conquest but rather large-scale raids, plundering and devastating the countryside and only occasionally attacking forts or major settlements.

The raids of this period are also largely confined to the central Anatolian plateau (chiefly its eastern half, Cappadocia), and only rarely reach the peripheral coastlands.

Under the more aggressive Caliph Hisham ibn Abd al-Malik, these raids have become more important and have been led by some of the Caliphate's most capable generals, including princes of the Umayyad dynasty, like Maslama ibn Abd al-Malik or Hisham's own sons Mu'awiyah, Maslama and Sulayman.

Gradually, however, the Muslim successes have become fewer, especially as their resources are drawn into the mounting conflict with the Khazars.

The raids continue, but the Arab and Byzantine chroniclers mention fewer successful captures of forts or towns.

Nevertheless, after a major victory over the Khazars in 737 had relieved them of pressure in the Caucasus, the Arabs have intensified their campaigns against the Empire: in 738 and 739, Maslama ibn Hisham has achieved a number of successes, including the capture of the town of Ancyra.