All Brass Prototype of the US Mark I Trench Knife with a 1910 bolo blade. By this time the 1910 bolo had quite a following as a fighting knife. This is the all brass prototype that appeared in Adrian Van Dyk’s List #115, p. 8, #61. Wild skullcrusher on this pattern from Springfield Armory. Also shown in Van Dyk’s article “Knuckle Knives of WWI” in American Blade.