He out-numbered them by four or five to one, and was on his own ground.

Whatever their intentions, at least he would be able to pretend afterward that he had acted in defence of the sacred treasure; and then, with the treasure in his possession, he would soon be able to recompense himself for a mere burned and looted palace! So he opened fire without notice, argument, or parley, and an ill-aimed volley shrieked over the heads of Cunningham's three squadrons.
Cunningham, unruffled and undecided still, made out through puckered eyes the six-horse carriage in which Miss McClean evidently was; it was drawn up close beside the wall, and two regiments were between it and his squadron.

He was recalling the terms of the agreement made with Jaimihr; he remembered it included the sparing of all of Alwa's men, and not the firing on them.
A thousand of Jaimihr's cavalry swooped from the shelter of the infantry, opened out a very little, and, mistaking Cunningham's delay for fear, bore down with a cheer and something very like determination.
They were met some ten yards their side of the half-way mark by Cunningham's three squadrons, loosed and led by Cunningham himself.
Outridden, outfought, outgeneralled, they were smashed through, ridden down, and whirled back reeling in confusion.

About a hundred of them reached the shelter of the infantry in a formed-up body; many of the rest charged through it in a mob and threw it into confusion.
Too late Jaimihr decided on more reasonable tactics.

Too late he gave orders to his infantry that no such confused body could obey.