how do you spend WAR BONDS on Battlefield 1.?

@UTAHBLACKSTONE

Warbonds work like Money in the game,

If you have something unlocked(unlocking different things work through level up specific Classes) for any Class/Vehicle like a Gun, Gadget, Melee Weapon or a differen Vehicle Loadout. So you can buy that with Warbonds.(If you have enough!)

To buy something you need to go to "Costumize Soldier" for any Class and "Costumize Vehile" on the Vehicle symbol in you'r Base if any is available.