The Prophet ﷺ appointed ʿAbdullah bin Jubair as the commander of the infantry during the battle of Uhud. They returned defeated, and that is what is meant by:-- "And the Apostle was calling them back in the rear. None remained with the Prophet ﷺ then, but twelve men."
جَعَلَ النَّبِيُّ ﷺ عَلَى الرَّجَّالَةِ يَوْمَ أُحُدٍ عَبْدَ اللَّهِ بْنَ جُبَيْرٍ وَأَقْبَلُوا مُنْهَزِمِينَ فَذَاكَ إِذْ يَدْعُوهُمُ الرَّسُولُ فِي أُخْرَاهُمْ وَلَمْ يَبْقَ مَعَ النَّبِيِّ ﷺ غَيْرُ اثْنَىْ عَشَرَ رَجُلاً