In addition to killing millions of military personnel, World War I sent home scores of soldiers with debilitating injuries -- namely, with a compromised ability to walk. Anybody who's ever had to use crutches knows how much pain they inflict on your armpits, hence the invention of crutches that let you sit down while hobbling around. The image pictured left shows a pair invented by Walter Clifford of London, who installed a small swing to the arm supports of his crutches. The seat, which resembled a bicycle saddle (or for what was presumably the budget version, a pad on springs), could be adjusted according to the user's height or be removed when not needed. You could also strap the crutches to your chest, leaving your hands and arms free to move around.
Read the full story in "Now the Crippled Soldier Can Do His Walking Sitting Down"