The War Droid was the most commonly used droid in the Cylon army. It was highly intelligent; able to adapt to changes in environment and enemy attack patterns hastily. Its primary weapon was a light repeating blaster and its secondary was a standard issue blaster rifle.
The War Droid, in essence, was the Imperium's replacement for the aging Battle Droid. War Droids, along with Assault Droids, formed the backbone of the Imperium army. They saw extensive use during the Sith-Cylon War, when Darth Trayus lead the Crimson Empire against the Imperium. Impressed once more by the droids' effectiveness, Trayus ordered a new batch to be processed in preparations for his next step in power.