Open up your Entrepot (what, you didn't get it?? awwww son, that's no good) to page 264.
"...Circular No.383 dated April 22, 1864, Gorgas transmitted the following request to his ordance officers in the field:"Please to advise as to the propriety of dispensing with knapsacks and substituting a light oil cloth six feet by three feet--so arranged as to be convertible into a shelter tent." <--Note, CS QM mentioning shelter tents
From Dalton, LC Oladowski forwarded the circular to his Division ordnance officers within the AOT with the request that "you will please call attention of the Brigade and regimental commanders to the above order and transmit as soon as practicable their different opinions." Few of the responses are extant, some from Clayton's brigade (AP Stewarts div) do.
The commanding officers of the 18th Ala, 38th Ala, and 32nd Ala, all supported the oilcloth over the knapsack. Clayton endorsed his commanders "I think the change proposed is advisable and should by all means be applied.
Brig. Gen. Randall Gibson was even more emphatic: "The oil cloth six feet by three feet is preferable to the knapsack in the field. Knapsacks are useless on active campaigns and the oil cloths should be carried and issued. I have been in the field since the war began and justifiably condemn knapsacks--they are totally unfit for [illeg] service". Post War Gorgas recalled that "in time, knapsacks were little thought of by the troops" and "were eventually voted out of order".
Ordnance Bureau circular No.42 dated May 24, 1864 Gorgas announced to the arsenals: "The manufacture of knapsacks will be discontinued, only those cut up will be made up. Existing contracts for knapsacks will be changed to furnishing enameled cloth or something else to save the contractor from loss. Instructions will shortly be issued as to a substitute for the knapsacks".
Webster goes on to mention several quarterly reports that reflect this.