I place no confidence in what this rascal tells me; nevertheless I think it right to inform you, Sir, that he declares positively that the Governor of Casale is his friend, and that, by promising him a considerable recompense, and by furnishing him with a pretext to save his honour, which may be done by giving him the order of his master, (which the Sieur de Lestang says is at Padua,) to receive the King's troops, we can make him do whatever we wish. That he can deliver up the town, and that the Governor of the citadel is his intimate friend, whom he can persuade to do whatever he shall order him. As for the castle, which I saw when I was passing through Casale, it is rather a sort of little citadel than a simple castle. The Sieur de Lestang says, that assuredly the governor of it will not submit himself to the orders of the Governor of Casale, although the latter has the command over him, because the aforesaid governor, whose name is Vialardo, is entirely devoted to the Spaniards; that this is a thing which he has heard from the Spaniards themselves, and that on the least change at Casale, or the march of troops towards it, the Governors of Valenza, Novara, and Pavia, have orders to send detachments of their garrisons to the aforesaid Casale, and that they will be infallibly let into the place through the castle. This Vialardo is brother of a secretary of the Duke of Mantua, who bears the same name, and who is also entirely in the Spanish faction.
However, when we shall have obtained possession of the papers, it is not impossible but we may be able to contrive something with the Governor of Casale, if he is in those sentiments that the Sieur de Lestang ascribes to him, and if he is the master to receive troops in the town and citadel. This affair, if conducted very secretly, and with the rapid march of a regiment or two of dragoons, might take the Spaniards so much by surprise, that they might not have any sufficient means in their power to be able to counteract it. If we were masters of the town and citadel, and had as large a number of troops as that which was destined to the execution of this affair, I am certain that the castle could not prevent any resolutions that we might wish to take. We might receive upon this subject important intelligence from an interview with the Governor of Casale. The difficulty is how to contrive it so as to discover his intentions, without the negociations passing through the hands of our rascal, in whom we cannot place any reliance. But, when we have the papers, if this affair was despaired of as far as regards the Duke of Mantua, and that the King thought that the plan I send to you, Sir, was worth trying, I would concert what was to be done with the Abbé d'Estrades, according to the orders I should receive upon the subject. I beg pardon, Sir, for troubling you with so long a letter; but I could not acquaint you in fewer words with the conduct of the Sieur de Lestang, and with what has passed between him and me.