Trench foot
Trench foot can be prevented by keeping the feet clean, warm, and dry. It was also discovered in World War I that a key preventive measure was regular foot inspections; soldiers would be paired and each made responsible for the feet of the other, and they would generally apply whale oil to prevent trench foot. If left to their own devices, soldiers might neglect to take off their own boots and socks to dry their feet each day, but if it were the responsibility of another, this became less likely. Later on in the war, instances of trench foot began to decrease, probably as a result of the introduction of the aforementioned measures; of wooden duckboards to cover the muddy, wet, cold ground of the trenches; and of the increased practice of troop rotation, which kept soldiers from prolonged time at the front.
Immersion foot syndromes
In the British Army, policies were developed to help the soldiers keep their feet dry - the surest way of preventing the disease. Soldiers were told to dry their feet, and keep them dry by changing socks several times a day. After the first year of the First World War, British troops were instructed to keep at least three pairs of socks with them and to frequently change them. The use of whale oil was also successful in combating trench foot. A British battalion in front line positions could be expected to use ten gallons of whale-oil every day.