During World War I, duckboards were put along the ground of trenches on the Western Front. This is because the trenches usually flooded. Mud and water would stay in the trenches for months. The boards helped to keep the soldiers' feet dry. It also helped stop soldiers get a disease called trench foot. Trench foot is caused by standing on wet, muddy ground for a long time. They also helped soldiers move along the trenches faster. Sometimes, falling from duckboards could be deadly. Some unlucky soldiers drowned in mud because of their heavy equipment.