غزوة الخندق
In 627 he participated in the Battle of the Trench and also in the Invasion of Banu Qurayza. In the Battle of the Trench, Muhammad divided the ditch into a number of sectors and a contingent was posted to guard each sector. One of these contingents was under the command of Abu Bakr. The enemy made frequent assaults in an attempt to cross the ditch, all of which were repulsed. To commemorate this event a mosque, later known as 'Masjid-i-Siddiq', was constructed at the site where Abu Bakr had repulsed the charges of the enemy.