"An order issued in 1873 (AGO G.O. 73 dtd July 10, 1873) flatly refused to issue boots to foot troops - leaving issue boots to Cavalry."
Actually, AGO G.O. 104 dtd Oct. 14, 1873 repealed order 73 and species the issue of four pair of bootees or two pair of bootees and one pair of boots to all soldiers, regardless of branch of service.
AGO (Adjutant Generals Officer) G.O. (General Order) 131 dated December 3, 1874 shows the table of Allowance of Clothing and shows 2 bootees and 1 pair of boots per year with no asterisk footnote specifying the 4 pairs of bootees with the option of two bootees and one boots to mounted men that showed up since 1857.
General Orders are alot of fun, they change so much from the regs. and often go back and fourth several times in the same year. I have not found another repeal of boots to foot soldiers after 1875, but I also don't have a complete set of all General Order issued from 1866-1891 (they are hard to find and VERY pricy when you can). I will try to consult other sources as I can (1880's regulations I have) to see what they say about clothing issues.
Chris Fischer
F-Troop