LINKThe Brits developed and issued this knife to their special forces during WWII.
More accurately William Ewart Fairbairn developed that knife, based upon his remarkably numerous affays during his more than two decades serving in the Shanghai Municipal Police.
https://en.m.wikipedia.org/wiki/William_E._FairbairnHe also wrote a manual on how to use it as in where to stick and cut folks with it which used to be available on the ‘net but IIRC was taken down by request of his descendants.
Fortunately our own Rex Applegate was far less circumspect about self-promotion and borrowed freely from Fairbairn....
https://www.amazon.com/Combat-Use-Double-edged-Fighting-Knife/dp/0873647351