The origins of this iconic dagger can be traced to Shanghai in the 1930s where W. E. Fairbairn and US Marine officers including Sam Yeaton carried out experiments in developing what they considered the perfect knife for close combat. When Fairbairn and Sykes became instructors for the Commandos, they refined the design which would evolve into the classic Fairbairn-Sykes dagger. The dagger was first used during early Commando raids into occupied Europe but saw action in every theatre of World War II. US Rangers and Marines who had trained with the Commandos took their Fairbairn-Sykes daggers home which also influenced the development of American Special Forces daggers.