Commander, you are able to send an army anywhere on the map regardless if it's an occupied spot or not. Using your army Rations you can select an empty spot on the map and send troops there to camp for a limited amount of time. The further you send your troops the more Rations will be consumed. Once all Rations are exhausted the army will automatically return home.
Note: Using March Speed Up items will decrease the travel time to the camp destination, but will have no effect on the Rations required to reach it since the distance remains the same.
When sending armies you can chose the point of departure, your home Base or all available camps around the map. If you decide to perform any action with any of your camp, this will consume all their Rations and after that action is done the remaining troops will return home. You can have a maximum of 5 camping armies. Each camp will gets a specific name for you to recognize them: Alpha, Bravo, Charlie, Delta & Echo. To send one of your camping armies onward, choose a target on the Map and from Send Army screen pick the appropriate camp for that action. Selecting that camp will display all troops that are currently in and the remaining Rations. From there it's just a tap away to send your camp to it's new target or destination
However you can not change or resupply any of your already existing camps, nor split one in two. If you wish to do so first you should get your squad home and send them out again. Each march starts with a fresh number of Rations automatically.
TIP: Camps are good way to reserve spaces, hide troops or even sneak attack some far away opponent without them realizing it. What else will you use them for Commander, is up to you.