The cover of darkness was used by armies to sneak out of their trenches to retrieve bodies, install barbed wire, repair trench defenses, or to go on raids. While some soldiers slept during the evening, officers and sentries kept watch over the no man's land and kept a keen eye and ear for movement outside of their trenches. If suspicious noises were noticed, a sentry may call out a password. If the password was not returned, or the raiding party fired at the sentry, a flare would quickly illuminate the battlefield, often resulting in a furious burst of yells, explosions, and machine gun fire.
Flares could also be used to signal groups from a distance, telling a force to attack, retreat, or flank an enemy. Officers will have the option of sending up a signal flare or an illumination flare but be careful, the flargun is not a useful weapon and an enemy raider could easily take you out before you can alert your men to arms.
Great job Rotzbua, Oelund, and Mach on the Webley Scott and "FEK" Flareguns!