A while back I read a book about the diet hardships of Civil War soldiers. It was entitled "Hardtack and Coffee".
No ding dongs or twinkies to be found
On the rush to Gettysburg 20+ mile forced marches were common, in the summer heat, wool uniforms, bad or no footwear, 10lb rifle-musket plus pack and/or roll. Hard biscuits as rations, water taken direct from streams, canteens startlingly small by today’s standards. I wonder how many died from heatstroke.