 Looting the countryside as they advanced, they arrived before Amorium seven days after their departure from Ancyra, and began their siege of the city on 1 August.The city's fortifications were strong, with a wide moat and a thick wall protected by 44 towers, according to the contemporary geographer Ibn Khordadbeh, and the caliph assigned each of his generals to a stretch of the walls.Both besiegers and besieged had many siege engines, and for three days both sides exchanged missile fire while Arab sappers tried to undermine the walls.