Applegate–Fairbairn fighting knife
The Applegate–Fairbairn fighting knife is a combat knife designed by Colonel Rex Applegate and William E. Fairbairn as a version of the Fairbairn–Sykes fighting knife. == History == While Applegate was a student of Fairbairn, he came up with a series of modifications to Fairbairn's Dagger and worked with Fairbairn on implementing them.
Source: Wikipedia — Applegate–Fairbairn fighting knife (CC BY-SA 4.0)