A key word search of the OR's indicates that the word whisky is used 309 times.There is some very interesting reading concerning it's use. The following are a few example.

To repulse a force double our own thus advantageously posted, free from a fatiguing march and liberally supplied with whisky (as the canteens of dead, wounded, and prisoners proved),

Whisky rations may be issued on the authority of division commanders when deemed essential to the health of the men from the inclemency of the weather or exposure in the swamps.

Supplies will soon be furnished and a supply of whisky will be sent to revive your fatigued troops.
Articles kept on hand for sale to officers, and for extra and special issues
to hospitals and troops: White sugar (pounds) 5,734
Whisky (gallons) 1,414