The next day the Muslims reached Damascus and besieged the city, which continued for 30 days. After defeating the Byzantine reinforcements sent by Emperor Heraclius at the Battle of Sanita-al-Uqab, from Damascus, Khalid's forces attacked and entered the city. With Khalid's divisions investing the city from the northeast, Thomas, the purported son-in-law of the Emperor Heraclius, surrendered the city to Ubaidah, who was besieging the Bab al-Jabiya (Jabiya Gate), on 19 September 634.