The first gas attack on the territory of Belarus was undertaken on the night of June 20, 1916 (old style, July 3 according to the new style) near the town of Smarhon on the front.
From the combat log of the 253rd P. Regiment: “At 3:30 the Germans played signals on their horns, then a few minutes later movement was detected suffocating gases from the village of Hadaki." The use of poisonous gases in the First World War was a major military innovation, and even then the range of toxic substances was quite wide: from relatively harmless (tear gas) to deadly poisonous (chlorine, phosgene, mustard gas). Thus, chemical weapons were one of the main ones, starting from the First World War and throughout the 20th century.
Photo: View of a gas attack on German trenches on the Eastern Front (GW)