Nowadays, water-bottles, aka canteens, are routinely issued to soldiers who serve in warm climates.
Was it the case in ancient times? In the Middle Ages?
The case I have in mind is the Battle of Hattin where the lack of water was one of the reasons for the Crusaders' defeat. Counterfactually thinking, had they brought along water-bottles, the outcome could have been vastly different. It has always puzzled me that they seemingly neglected this, since after almost 90 years in the East, they should have grasped by then the importance of carrying some water with you. Can anyone shed light on this issue?