We have already agreed that, after the withdrawal of the hypocrites at Uhud, the number of Muslims left in the field was seven hundred. The Battle of the Ditch took place only two years after the Battle of Uhud. During these two years, no large accessions to Islam are recorded in history. An increase during this time in the number of combatant Muslims from seven hundred to three thousand is not to be expected. At the same time, it does not stand to reason that between Uhud and the Ditch there was no rise in the number of combatant Muslims. Islam continued to add to its numbers and we should expect some increase between the Battle of Uhud and the Battle of the Ditch. From these two considerations, it seems to follow that the estimate which puts the number of Muslim combatants in the Battle of the Ditch at one thousand two hundred is correct. The only question to be answered is, why some authorities put the number at three thousand and some at seven hundred. Our answer to this question is that the two figures relate to two different stages of the battle. The Battle of the Ditch was fought in three stages. We had the first stage before the enemy had come near to Medina, and Muslims were engaged in digging the ditch. During this time, we may well assume that in removing the excavated earth to a distance, children and, to some extent even women must have come in to assist. In the digging of the trench we may, therefore, assume that there were altogether three thousand souls employed on the Muslim side. The number included children and some women. The children were able to help in carrying the earth, and women who always vied with the men in helping all Muslim campaigns, must have been useful in doing many ancillary jobs connected with the digging. There is evidence to support this assumption. When the digging started, even children were asked to come. Practically the whole population took part in the digging. But as soon as the enemy arrived and the battle began, the Prophet(sa) ordered boys under fifteen to withdraw from the scene of operations. Those above fifteen were allowed to take part if they were so minded (Halbiyya, Vol. 2). From this it appears that at the time of digging, Muslim numbers were much larger than when the battle began. At the time of the battle the very young boys had all withdrawn. Estimates which put the Muslim numbers in the battle at three thousand relate only to the digging, and those which put the figure at one thousand two hundred relate to the actual battle in which only grown-up males took part. The only estimate we have not accounted for is that which puts the figure at seven hundred. Even this estimate, according to us, is correct. It has been proposed by as reliable an authority as Ibn Ishaq, who is supported in this estimate by no less a person than Ibn Hazm. It is difficult to question this estimate. Fortunately, when we turn to the other details of the battle, even this estimate turns out to be correct. There is evidence to show that when the Banu Quraiza, against their plighted word, joined the enemy, and decided to attack Medina in the rear, the Holy Prophet(sa), having been apprised of their evil intention, decided to post guards in the part of the town exposed to the attack of Banu Quraiza. This part of Medina had originally been left undefended because the Banu Quraiza were in alliance with Muslims. And it was assumed that they would not let the enemy attack the town from their side. It is known that when the defection of the Banu Quraiza was reported to the Prophet(sa) and it became evident that Muslim women, considered safe in this part of the town because of the alliance, were no longer safe, the Prophet(sa) decided to send two forces, of two and three hundred men, to guard two different parts of the now exposed town. The Prophet(sa) ordered them to raise occasional cries of "Allahu Akbar", so that the main Muslim forces should know that the Muslim women were safe. The estimate of Ibn Ishaq, therefore, which puts the number of combatants in the Battle of the Ditch at seven hundred, is also correct. If five hundred men out of one thousand two hundred were sent to guard the rear of the town, only seven hundred could remain. Thus all the three estimates of the number of the Muslim army in the Battle of the Ditch turn out to be correct.
To defend the ditch, therefore, the Holy Prophet(sa) had only seven hundred men. True, the ditch had been dug. But to face and to repel an army as large as the enemy had, even with the help of the ditch seemed well-nigh impossible. But as usual Muslims trusted their God and relied on His help. Their small force waited for the enemy host, while the women and children had been sent to two apparently safe parts of the town. When the enemy reached the ditch, they were amazed because this stratagem had never been used before in any Arab battle. So they decided to camp on their side of the ditch and to deliberate over methods of attacking and entering Medina. One side was protected by the ditch. A second side had hills with their natural protection. A third side had stone houses and groves of trees. It was impossible for the enemy to make any sudden attack on any part of the town. The enemy commanders took counsel together and decided that it was necessary to try to wean the Banu Quraiza, the Jewish tribe, still living in Medina, from their alliance with the Muslims and ask them to join the Arab confederates in this critical onslaught against Medina. Only the Banu Quraiza could give them a way to the town. At last Abu Sufyan(ra) selected Huyai bin Akhtab, chief of the banished tribe of Banu Nadir and principal instigator of Arab tribes against Medina, and appointed him to negotiate with the Banu Quraiza for facilities to attack the town from the rear. Huyai bin Akhtab went to the Jewish fortress to see the leader of the Banu Quraiza. At first they refused to see him. But when he explained that this was a very opportune moment to defeat the Muslims, he succeeded in winning over one of the Quraizites, Ka’b. He explained that all Arabia had turned out to attack and destroy the Muslims. The army which stood at the other side of the ditch was not an army, but an ocean of able-bodied men whom the Muslims could not possibly resist. Ultimately it was agreed that as soon as the army of disbelievers succeeded in forcing the ditch the Banu Quraiza would attack that part of Medina to which the Holy Prophet(sa) had sent all the women and children for safety. This plan, it was believed, would smash the Muslim resistance, and prove a death-trap for their entire population—men, women and children. If this plan had met with even partial success, it would have cost the Muslims dear and made things very difficult for them. They would have had no escape from this death-trap.