“A strong body of cavalry having meanwhile charged the two regiments supporting the left of the front line, but being repulsed, rode in towards the 2nd brigade under cover of some sand hills; and observing an interval between our regiment and that on its left, immediately advanced to charge through it, in which they must have succeeded had they not been checked by a prompt and well-directed fire from our Light company, for, unfortunately, the left battalion of the brigade having mistaken them, from their green uniforms for Hompesch’s Hussars (attached to our army) not only suffered them to ride quietly along their front, but kept calling out to us not to fire upon them; this error having, however, been fortunately discovered when the cavalry were within a hundred paces of us, and in the act of wheeling up to charge, the regiment halted, and opening a steady and rapid platoon fire immediately after that of the Light company, brought down a great number of men and horses, threw them into complete disorder and compelled them to a precipitate retreat, though many of them had even arrived within a few paces of the interval on our left. Had not the Royal Irish so timely opened its fire, the brigade must have been broken through, and the enemy penetrated to the second line, which in firing on them must at the same time have fired upon us. This cavalry, by a strange coincidence, happened to be the 18th regiment of heavy dragoons, and afterwards (when a troop of this corps was taken in the desert) they said, pointing to us, ‘had it not been for that regiment it was all over with your expedition.’”