During World War I Germany was known for their gas attacks. They would release gases, such as mustard gas, across no mans land to waft into the enemy trench. The gases that were released had many harmful effects. When they came in contact with skin, it scorched it and left painful welts. If the eyes were exposed, it was blinding. When this gas was inhaled it burnt the lungs, making them incapable of receiving air. Enough though these gases were intended to only harm the enemy, they often traveled through the air to nearby cities, because of this civilians were also forced to wear gas masks.