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
Yusuf Ali, Abdullah. Translation and Commentary of the Quran. (surah 59 verse 6 Quran Arabic with English Translation & Commentary (Tafsir) by Abdullah Yusuf Ali, Free Download (quran4u.com)