The Doughboy knuckle-sandwich
Via the U.S. Army Ordnance Training and Heritage Center:
This Model 1918 Mark I trench knife was made in France by Au Lion in 1918 for use by US troops during World War I. The US also produced these knives during the war, but having a French contract allowed for expedited distribution to US troops already overseas. The knife has a 6.75” doubled edged steel blade and a bronze handle with cast spikes on each of the knuckles, and a distinctive 4-sided nut on the end. Stamped in the handle: U.S.1918. On the opposite side, engraved in the ricasso: [Au Lion logo] / AU LION. The Model 1918 Mark I knives were also distributed during World War II, though often modified, for example removing the knuckles.