Bruising and Bleeding. Bruising or bleeding after an injury is normal. However, some people have disorders that cause them to bruise or bleed too easily. Sometimes people bleed without any obvious triggering event or injury.
The skin of victims of mustard gas blistered, the eyes became very sore and they began to vomit. Mustard gas caused internal and external bleeding and attacked the bronchial tubes, stripping off the mucous membrane. This was extremely painful and most soldiers had to be strapped to their beds.
A second gas attack, against a Canadian division, on April 24, pushed the Allies further back, and, by May, they had retreated to the town of Ypres. The Second Battle of Ypres ended on May 25, with insignificant gains for the Germans. The introduction of poison gas, however, would have great significance in World War I. Immediately after the German gas attack at Ypres, the French and British began developing their own chemical weapons and gas masks.