The destruction of an American cargo ship containing mustard gas led to many casualties in Bari, Italy, in December 1943. In both Axis and Allied nations, children in school were taught to wear gas masks in case of gas attack. Germany developed the poison gases tabun, sarin, and soman during the war, and used Zyklon B in their extermination camps. Neither Germany nor the Allied nations used any of their war gases in combat, despite maintaining large stockpiles and occasional calls for their use. Poison gas played an important role in the Holocaust. Britain made plans to use mustard gas on the landing beaches in the event of an invasion of the United Kingdom in 1940. The United States considered using gas to support their planned invasion of Japan. The contribution of gas weapons to the total casualty figures was relatively minor. British figures, which were accurately maintained from 1916, recorded that 3% of gas casualties were fatal, 2% were permanently invalid and 70% were fit for duty again within six weeks. Death by gas was often slow and painful. According to Denis Winter ("Death's Men", 1978), a fatal dose of phosgene eventually led to "shallow breathing and retching, pulse up to 120, an ashen face and the discharge of four pints (2 litres) of yellow liquid from the lungs each hour for the 48 of the drowning spasms." A common fate of those exposed to gas was blindness, chlorine gas or mustard gas being the main causes. One of the most famous First World War paintings, "Gassed" by John Singer Sargent, captures such a scene of mustard gas casualties which he witnessed at a dressing station at Le Bac-du-Sud near Arras in July 1918. (The gases used during that battle (tear gas) caused temporary blindness and/or a painful stinging in the eyes. These bandages were normally water-soaked to provide a rudimentary form of pain relief to the eyes of casualties before they reached more organized medical help.) The proportion of mustard gas fatalities to total casualties was low; 2% of mustard gas casualties died and many of these succumbed to secondary infections rather than the gas itself. Once it was introduced at the third battle of Ypres, mustard gas produced 90% of all British gas casualties and 14% of battle casualties of any type. Mustard gas was a source of extreme dread. In "The Anatomy of Courage" (1945), Lord Moran, who had been a medical officer during the war, wrote: Mustard gas did not need to be inhaled to be effective—any contact with skin was sufficient.