59:6
What Allah has bestowed on His Messenger (and taken away) from them – for this ye made no expedition with either cavalry or camelry: but Allah gives power to His messengers over any He pleases: and Allah has power over all things.
Neither cavalry nor troops mounted on camels were
employed in the siege. In fact the enemy surrendered at the first onset. Allah accomplishes His purpose in various ways, according to His wise Will and Plan. In some cases a fight is necessary. In some cases the godly attain their objective and overawe the forces of evil without actual
fighting.
References:
Yusuf Ali, Abdullah. Translation and Commentary of the Quran. (surah 59 verse 6