Coffee was so important in wartime America during World War II that the government rationed it briefly so soldiers could get enough.
Stories say that in Vietnam, soldiers ate instant coffee to stay awake.
Coffee was one of four staples for Civil War soldiers, along with beans, beef and hardtack.
After Boston Tea Partiers dumped that tea in the harbor during the American Revolution, coffee drinkers were considered patriotic.
Coffee can give a soldier the alertness they need in times of prolonged sleep loss or during dangerous combat situations.
Now, the U.S. military puts caffeine in food, gum, and other beverages to keep soldiers alert and ready for anything.
The site Military com calls coffee "the lifeblood of the military" . The article states:
Coffee has been a staple of the American military ever since the first Revolutionary patriot signed up to throw the tea into Boston Harbor — fueled entirely for their hatred of tea. Our love of java necessitated the creation of instant coffee in the Civil War, and we’ve been drinking it ever since.
During the U.S. Civil War, coffee was of paramount importance to soldiers of both the North and South. Says the site CivilWar.com :
Coffee was a most desirable staple and some soldiers considered the issue of coffee and accompanying sugar more important than anything else. Coffee beans were distributed green so it was up to the soldiers to roast and grind them.
The task for this most desirable of beverages was worth every second as former soldier John Billings recalled: "What a Godsend it seemed to us at times! How often after being completely jaded by a night march... have I had a wash, if there was water to be had, made and drunk my pint or so of coffee and felt as fresh and invigorated as if just arisen from a night's sound sleep!"
Another article on Civil War rations that has been taken down from the Web reported:
Coffee was really more important to the average soldier than anything else he could beg, borrow, or steal. It got him up in the morning and put him to bed at night. Properly made it could float a horseshoe, or dissolve it. Like the Missouri River, it was too thick to swim in and too thin to walk on, and would make a jackrabbit spit in a rattlesnake’s eye.
There is no record of exactly what type of coffee was issued to the Northern troops. Neither the Library of Congress nor Official Records give any clue, other than the fact that the North bought the very best coffee it could buy. The South bought anything it could buy.
Today there are detailed records about the coffee and other caffeinated products the U.S. military feeds its personnel—and there are many. Products soldiers take into the field with them include caffeinated beef jerky called Perky Jerky, mints, gum, energy bars and applesauce, which the military calls Zapplesauce. These products contain about 100 mg of coffee per serving. That compares to about 163 mg in an average cup of Joe.
Wired.com has an excerpt  from the book Caffeinated: How Our Daily Helps, Hurts and Hooks Us by Murray Carpenter that states:
'A chemical substance which stimulates brain, nerves, and muscles, is a daily necessity and is used by every single nation. When there is fatigue and the food is diminished such a stimulant is indispensable, and must be an ingredient of every reserve and emergency ration.’ That’s from the 1896 Report of the Secretary of War, and more than a century later, the U.S. military is still trying to figure out how best to caffeinate soldiers.
The Wired story says some soldiers put instant coffee in their cheeks like chew. Similarly, the military gum delivers the caffeine sublingually, so it only takes five or 10 minutes for the invigoration to begin as compared to a half hour or more for pills or beverages.
Soldiers are getting a new arsenal of powerful weapons, but these are the kind you eat. Beef jerky, chocolate pudding, gum, mints, juices – all caffeine-enhanced – are now standard weapons to fight soldier fatigue and enhance alertness. The U.S. Department of Defense and military divisions of Canada, Australia, New Zealand and the United Kingdom are jointly researching – and recommending – the use of caffeine on the battlefield.
Caffeine has long been part of a soldier’s toolkit. In 1942, Winston Churchill asserted that tea was more important to his soldiers than ammunition. In Vietnam, soldiers literally ate instant coffee to stay awake.
The gum developed by Walter Reed Army researchers and Wrigley’s Gum was originally called Stay Alert but is now called Military Energy Gum. American soldiers like the product, and now Israeli pilots keep caffeinated gum with them on mission that go on longer than 48 hours, CaffeineAndYou.com says.
Two pieces was more than enough to feel the effects, the biggest difference between the usual energy drink rush and a caffeinated gum rush is that much more caffeine is absorbed through the blood vessels under the tongue than through the stomach. The package states that within 15 minutes of chewing, 99% of the caffeine has been absorbed. … if you’re looking for a speedy caffeine fix there’s no beating this. … A word of caution to anyone wanting to try this gum, multiple people I talked to said that in the 10 minutes following the 5 minute cinnamon flavor they felt what they could only describe as “sick.” Not a vomit sort of sick but they said it was similar to feeling the need to gag. I assured them they would be fine and to stick it out and all of them ended up loving it. If the gum is bitter it means there is still caffeine left to absorb, once the caffeine is gone it will be a mild enjoyable taste for as long as you choose to chew.
Like the gum, the mints can be taken sublingually or under the tongue for the quickest, most direct impact.
There is little word in these stories about unsafe levels of caffeine, though soldiers should be aware that heavy caffeine use can cause insomnia, nervousness, muscle tremors and stomach upset. Excess caffeine can also cause irritability, headaches restlessness, excessive urination and fast heartbeat.
These side effects come with what MayoClinic.org  calls heavy caffeine use of 500 to 600 milligrams per day.
A Viter Energy blog explores how much caffeine is safe for adults : About 300 to 400 milligrams of caffeine are right for an adult, about 100 mg for adolescents and none for children.
Stories of coming back from a downfall after great success are inspiring for anyone—even for young people who haven’t made their mark on the world yet. History and mythology are filled with people who were at the height of success, crashed and came back again.
Sometimes, people need to lose everything material to realize that they didn’t need it, or that the health and safety of their families are worth more than all the success and gold in the world. Sometimes people come back even stronger and more successful than before they “fell.”
Unless you work outdoors or indoors in a job where you are physically active all day, it can be difficult for some people who have desk jobs to stay awake at work without caffeine.
Maybe the most important thing you can do to make sure you don’t nod off at work is to get a good night of sleep, at least 7 to 8 hours, at a regular time every night. Boredom can also cause you to nod off. Other than getting a good night’s sleep and having a fascinating job, there are things you can do to stay awake.
How do investment bankers stay awake on their 18-hour shifts?
Investment bankers work such long hours that many resort to chemical stimuli. There have been rumors of methamphetamine and cocaine use among investment bankers to burn the midnight oil. Other investment bankers take Ritalin or Adderall, which are given to children with ADHD but which are stimulants for adults. But the mainstay is probably coffee, energy drinks, and other concoctions containing caffeine.