[Copy] War department 18^th August 1791. Sir, I have the honor to enclose a duplicate of mine to you of the 11^th instant — and also a duplicate of mine to Major General St Butler of that date and of this day. I presume Captain Newman will not arrive at Fort Pitt until the 26^th instant, and Captain Jones about the 10^th of September. No other troops are on their marches, excepting a party of about thirty from New Hampshire, who have not yet arrived at Brunswick. Jones' detachment consists of about Ninety two Negroes. All the Stores which have been written for have been forwarded, either from Fort Pitt or this place, excepting the 5½ inch shells, which cannot be obtained in season for the campaign. As the most expeditious mode I sent out some to West-point and expect them here hourly. When they arrive they shall be forwarded. Some reports have been written raised in this city, as to the powder furnished Mr Broodgen by Mr Joseph Miller was not of good quality, supposing that made by his Workmen Jacob Tresses. I have had some rounds of Jacob Tresses's make proved, by taking one piece of each sort, to wit, Cannon, Musket and rifle, and producing a 24^th ball out of a 5½ inch mortar, elevated at 45°. placing the powder in the chamber of the mortar loose and putting a piece of paper over the mouth of the chambers. The powder to be well dried in the sun. This is the surest possible mode of proving powder, and the powder as proved had been remanufactured from damaged public powder, and was found upon trial to be equal to the best cross powder. It is considered that if one ounce will under the above circumstances project a 24^th ball 30 yards that it is sufficiently strong — most of the powder which was tried as above projected the ball at an average 40 yards. Mr Miller has made an affirmation that the powder furnished the public was made of refined salt petre, and was villest crude, it not inferior to that which has been proved here. I mention this circumstance to you, lest the report may have reached you, by some other channel. you will of course direct the powder to be proved in the manner stated, by Major Ferguson. I have no doubt that you will find it entirely good. I am well readily persuade that there is a sect of Maveison, which must be kept carefully from the troops — for unless they rely with confidence on the goodness of their powder, no dependence can be placed on their exertions. The worst sects I am pretty confident emanated in a derangery or some dealers in the same article. I sincerely hope that you will have received your whole force, and have commenced your operations by the time you receive this letter, which I consider as the last you will receive at Fort Washington. I cannot easily express to you the anxiety of the President of the United States, that the campaign should be entirely successful and issue in a just and honourable peace with all the tribes. He is persuaded that you will leave to exertion every nerve under your command — and that you will establish a sure mode of communication with this office, while you are on the expedition. With great respect I have the honor to be Sir Your most obedient Hum. Servant [Signed] Knox Sec^y of War. Major General Arthur St Clair [Endorsed: No —]