It's WW2. You're a general, sitting in a tent. You have a radio, a map, some markers and unit figurines in front of you. Win the battle. Unlike other WW2 real-time strategy games (Company of Heroes, Men of War, etc.), you are not some omniscient being floating above the battlefield. You have units to control, but you can't see them. There are enemies out there, but you can't see them. Your only link to the battlefield and your units is the radio. Your units will make periodic status reports to you over the radio, and you'll give commands over the radio. Unfortunately, units can be a little... unreliable. Sometimes you'll lose contact with them, other times they'll exaggerate how much danger they're in, and sometimes they'll get lost. It's up to you to sift through the available information and make the correct decisions to win the battle.
Since the player will be removed quite removed from the action, you won't be able to micromanage your units, meaning combat can be simple. Most of the strategy will be in positioning your units, and each terrain type will offer different amounts of cover or defence.
For now, each unit has health, damage, and defence (% reduction of damage). For next time I want to add flanking; having multiple units surround a unit negates its defence. Flanking will be important when an enemy unit is entrenched in a town giving them 90% defence.
In the future I'll add morale (panicking, retreating), terrain defensive bonuses, and range damage penalties (fighting at range means less damage dealt).