The Massacre of Veld was a lethal gas attack that occurred on November 10, 1918 in the town of Veld, Belgium during World War I. The attack was orchestrated by General Erich Ludendorff of the Imperial German Army and his loyal ally Doctor Isabel Maru, also known as Doctor Poison. The massacre wiped out the entire population of Veld, just after the town has been liberated by Wonder Woman and the Wonder Men. The massacre was an attempt by Ludendorff to show the might of the German Army to the rich and powerful people at the Gala that was being held nearby.
During World War I, Wonder Woman and the Wonder Men fought in the Battle of Veld on November 9, 1918, successfully liberating and reclaiming the town of Veld, Belgium from the Imperial German Army. Just the next day, General Erich Ludendorff held a gala just nearby, and wanted to show the Germans' strength in the war following their loss by testing their new chemical weapon.
Horrified at the death caused by the gas, Wonder Woman told Steve Trevor that she felt the massacre was her fault for letting Ludendorff, who she believed was Ares, stay alive. She rode to a complex behind Castle Veronique and engaged with Ludendorff directly, where she beat him in combat and killed him.