The Army's adoption, in the field in the warmer climates, of non-regulation canvas clothing goes back quite a bit before this. Had it's origins in canvas clothing intended for stable fatigue duty. Particularly trowsers as they were the most susceptible to wear and tear by hard campaigning.
From Campaign Clothing: Field Uniforms of the Indian War Army 1872-1886 by Lee A. Rutledge, 1997
". . .but Captain John G. Bourke, 3rd Cavalry, documented their field use about 1873. Captain Bourke had this to say in On The Border With Crook (1892):
"At Camp Verde (Arizona Territory) we found assembled nearly all of (General George) Crook's command, and a dirtier, greasier, more uncouth-looking set of officers and men it would be hard to encounter anywhere. Dust, soot, rain, and grime had made their impress upon the canvas suits which each had donned. . . ." Presumably, their outfits were Army-issue stable frocks and overalls.
. . Their use led directly to adoption of canvas fatigues in the 1880's, the canvas combat uniform of 1898 and, ultimately, to modern-day military field outfits."
"Without a doubt, the common practice of wearing canvas work garments on campaign had the greatest impact; within a few years only canvas field garments were issued."