civil war food rations consisted of
salted meat, hardtack (plain biscuit of flour and water), a little sugar, and salt.
in the days before artificial preservatives,
food supply chains were riddled with corrupt food contractors,
charging the government top dollar for rotten, stale, and insect-ridden food.
they'd even cut ground coffee with sand and dirt.
for a bit, the army tried "essence of coffee", a concentrated proto-instant coffee;
(coffee/milk/sugar boiled into a thick goop, reconstituted by mixing with water)
it tasting bad, and caused diarrhea (from the spoiled milk, sold by corrupt dairymen),
so army officials began requesting coffee be delivered in whole-bean form.
this which kept coffee fresh, and made it the best thing on the menu.
even if there was no time to boil, soldiers would chew on beans.
there were brewing recipes for "the new iron stove" or campfire.
using a wire bail, tie a "mucket" (tin dipper) to the end of a stick.
boil coffee/water to the desired dark hue, and strong enough to float an iron wedge.
make "three full dishes" by adding 1oz coffee to 3/4 pint water,
or 2 "great spoonfuls" ("heaped tablespoonfuls") to 1pint water.
serve up to 100 men by using 10lbs green coffee, or 8lbs roasted/ground.
they'd often crumble hardtack into the coffee.
the boiling process kills water-borne pathogens,
so coffee was safer than water straight from rivers, ponds, and puddles.
The Union had many advantages;
two-thirds of the population was The North,
which controlled most of the heavy industry, railroads, financial reserves,
.....and supplies of coffee beans!