From the Memoirs of James II, dated from the period just following the 30YW:

CAMPAIGNS OF THE DUKE OF YORK 1654

But though neither ours, nor his could meet with any of these powder-carriers, yet by an accident hapening amongst themselves, one of their Convoyes chanced to miscarry; For one night as wee "were with Mr. de Turenne, visiting the guards, wee perceived a great blaze of fire, quick and violent like that of the blowing up of gunpowder; and it seem'd to us, as if it had been at the quarter of Monsr. de la Ferte : But as (we) went down that way to inquire of it, our Sentinels who were upon the heigth of Mouchy, inform'd us, that they had likewise seen it, and that it was not where wee had imagined, but on the plaine farr beyond those quarters to wards Lens, which caus'd us to wonder the more what it might be. The next morning wee were fully Satisfied concerning it, that an entire Regiment of horse, consisting of Six score, going from Douay to the Enemie's Camp, all of them Officers as well as Souldiers having behind them a bagg of powder, besides about fourscore horses laden with hand grenades, which were led by Countrymen on foot, had been all blown up, but by what accident, none of those who were brought prisoners into the Camp could tell. Indeed it was a very dismall object, to behold a great number of poor men, who were brought into our Camp with their faces disfigur'd and their bodies burnt by powder, so that few of them recover 7 d> their Companions having been all kill'd outright. These prisoners were brought in by some of our partys who were out on that side of the Country, who seeing the flash at a great dis tance, rode up to the place to gaine a more clear knowledge of the matter; they also brought along with them some few scorch'd horses, and a paire of kittle drums which belong' d to that Regi ment, and all the men who had any life remaining in them.

I happen 'd since, when I was in Flanders, to talke with a Lieutenant of horse who was the only man that could give an account, how that accident befell them; for seeing his face had been burnt, I casually ask'd him how he came by that misfortune? He answer'd me, that it was by the blowing up of powder at such a time near Arras; and upon my examining him concerning the particulars of it, he told me, That happening to be in the Rear of the whole Regiment, he saw one of the Troopers with a pipe of tobacco lighted in his mouth; wherupon he rode up to him, and taking it gently from him, threw it away after which he beat him with his sword: The Soldier being drunke, pull'd out his pistol, and pre- sen ted it to his breast; upon which the Lieutenant threw himself from his horse apprehending what might happen, and the Trooper at the same instant firing at him, it lighted on the bag behind the sd Lieutenant's horse, which taking fire, blew it up, and so, from one successiuely to the other who was next, it spred through the whole Regiment: he being on the ground escap'd best cheape, having only his face, his hands, and some parts of his bod scorched.