In most missions, you will start with a few units and a partially developed base. You may find that you need more than a single squad, or even multiple squads, of Rifle Troopers to achieve victory. This is where the miracle of telecommunications comes into play. Units can be deployed at any base under your control that has a Drop Site. The locations have various names such as Radio Stations, Radio Posts and Satellite Centers, but they all function the same way.
To deploy a unit, select a base and then either left-click the unit icon in the Control Grid or press the corresponding hotkey. You must also have sufficient resources, an available Dropship as well as control of the building required to support that unit type. Once selected, the unit will rapidly be delivered to an open Drop Site.
All units require a certain amount of Supplies to be deployed. Supplies can be obtained by capturing new bases or recovering Supply Caches that are located on the Battlefield. Only bases that have Supply Depots attached to them will increase the amount of available Supplies. if you lose control of a base you will also lose access to its Supplies. Supplies gained via Supply Caches are permanent. It is possible to have a negative amount of Supplies if you lose control of a base or receive new units from a mission event. There are no penalties for having negative Supplies but you will not be able to recruit new units until you are no longer in the red.
A unit icon will appear in the Unit Bar bracketed by a Dropship until it arrives. If all Drop Sites are currently occupied, their unit icon will appear brown and have a small stopwatch at the bottom. It is possible to order units in the queue to be sent to a new location by selecting it and pressing [Q] then selecting an open Drop Site at another location. If you have sufficient Dropships, units waiting to be deployed can be redirected to other Drop Sites (even temporary ones) by clicking on the queued unit in the Unit Bar, pressing [Q] and then selecting a different Drop Site.