If you wish to survive the open world of Dying Light The Beast then you need to get the best weapons and collect as many resources as possible. One of the sources of both are the military convoys. Military convoys are large armored vehicles and all of them are marked on your map so you can easily find them.
To find these convoys look for vehicles icons on the map but simply reaching their location isn’t going to work. You need to find the keycard to open them.
How to Open Military Convoys in Dying Light The Beast
Each military Convoy has a zombie wearing military gear near it. Take it down to get the card.

Military convoys can be in the shape of armored vehicles or sometimes abandoned train cars. No matter the type, there is always a Bitter wearing military gear in the vicinity.
The good news is that they are easy to kill. There is nothing scary about them and they go down it one shot. Loot their bodies to get the cards and open up the convoy.
Sometimes there will be puzzles associated with the convoy or some extra steps. For example, The Elite legendary pistol is also inside a convoy but the keycard pad is unpowered. You’ll have to power it before using the card.

Before leaving the convoys make sure to check them for ammo. There are always storage compartments on the sides where you can find some ammo for your weapons.