During World War One, trench foot was a major issue on the Western Front due to inadequate drainage, causing feet to swell, blister, and turn blue. Tight boots and wet socks worsened the problem, leading to gangrene and amputation in severe cases. By 1915, many soldiers required treatment for trench foot, reducing active troop numbers and lowering morale. Preventative measures included changing socks twice a day, using whale oil on feet, and implementing mechanical pumps to reduce flooding in trenches.