When silent operations are absolutely critical, or when you somply run out of ammunition, the combat knife can be your best friend. Knives were used in WWII for both hand-to-hand combat, and for slitting the throats of unsuspecting people when the combatant was attempting to be silent. The Fairbairn-Sykes Dagger was made before the War, designed to have good grip, and weight distribution, ideal for close combat. The SAS and other special forces used the dagger, so it was well known on the battlefield. The knife became some kind of symbol of the special forces, and inspired many other daggers worldwide. It remained in service for decades, and it's variants are still in production.
Fairbairn-Sykes Dagger on Wikipedia