How to grow and make your own tea
There are many other links on this subject, too.
Now, and in general, most coffees are made from beans (usually ground up or other-wise made with a mortar and pestle [http://en.wikipedia.org/wiki/Mortar_and_pestle]), while most teas are made from some roasted roots and often leaves.
It is important to many that something warm to drink at the end or even during a security patrol is “good for morale”, especially during harsh weathers. “Teas” provide such a method. Said another way, if one wants to enhance their own security, then enhancing “morale” of those who provide such security is not a bad way to go. After all, the bad people are subject to similar situations, so the better we make things for our own people, the better off we will always be. Even warm “thrifty” ramen soups are really wonderful to those who consume them at 0300 in the local morning, for example.
Last one can offer coffees or teas that have caffeine in them, and that always helps, too. Any perceived “boost” is always appreciated. But being warm and often salty or slightly sweet drinks are always a good idea; and whether they have caffeine in them or not is secondary.
PS Now making it can be pretty simple, too. Basically, if one can boil water on a wood stove or in a fireplace or something similar, then they can probably figure it out.