I'm drunk as fuck and went to get a glass of water and thought about how hundreds of thousands of ancient soldiers able to get water?
A similar question has been answered by /u/23092908 and /u/Protosmoochy at the following URL:
https://www.reddit.com/r/AskHistorians/comments/1no3b7/how_were_ancient_and_medieval_warriors_able_to/