Close combat wasn’t used a lot at the beginning of World War 2 since firearms were quite prevalent. But the commandos had to be as stealthy as possible when carrying operations out; so despite the efforts to equip their weapons with silencers (which were quite inefficient at that time), they developed a fearsome efficiency in close combat, combining technique (like hitting specific parts in the neck to lead to almost instant death, putting the hand on the victim’s mouth to prevent them from screaming, etc.) and the use of Fairbairn-Sykes fighting knife.
(source: Wikipedia) Fairbairn-Sykes fighting knife was created by William Ewart Fairbairn and Eric Anthony Sykes, based on concepts they learned while serving on the Shanghai Police, then the British Army. This knife is mostly known because it was used by commandos from Great Britain and Commonwealth during WW2. It has been improved over the years and is still being produced today.