Before chocolate candy was developed, cocoa was almost always a drink. And far before chocolate milk became a kid's staple, cacao was a manly beverage, reserved for warriors.
Cacao was cultivated and consumed by the Olmecs and Mayans, but is most famously associated with the Aztec civilization. Montezuma the II, who kept a huge storehouse of cacao (supplied by conquered peoples from whom he demanded the beans as tribute) and drank 50 golden goblets of chocolate a day, decreed that only those men who went to war could imbibe cacao, even if they were his own sons. This limited chocolate consumption to royals and nobles who were willing to fight, merchants (their travels through hostile territory necessitated their taking up of arms), and warriors. For the latter, chocolate was a regular part of their military rations; ground cacao that had been pressed into wafers and could be mixed into water in the field were given to every solider on campaign. The drink provided long-lasting nourishment on the march; as one Spanish observer wrote, “This drink is the healthiest thing, and the greatest sustenance of anything you could drink in the world, because he who drinks a cup of this liquid, no matter how far he walks, can go a whole day without eating anything else.”
All Aztecs thought of both blood and chocolate as sacred liquids, and cacao seeds were used in their religious ceremonies to symbolize the human heart – harkening to their famous ritual in which this still-beating organ was torn from a sacrificial victim’s chest. The connection between blood and chocolate was especially strong for warriors, and it was served at the solemn initiation ceremony of new Eagle and Jaguar knights, who had to undergo a rigorous penance process before joining the most elite orders of the Aztec army.
As chocolate was carried around the world, it was changed considerably, but still made into a manly beverage as nutritious sustenance for Arctic explorers and soldiers at war. The Art of Manliness has an extensive history of hot cocoa and its use, including tips for making yours better. Link