[ArmyTeach]

An old Muslim strategy. The Sheiks would send young unmarried men(those unlikely to have marital prospects because the Sheik had married all the likely young women)to kill his enemies. The young men were called 'hashishim' (assassins) and were stoked up on hash/marijuana/whatever to boost their courage and remove their inhibitions before they went out to kill.

[Joe 6-pack]

The Somalis did the same thing with khat. Kind of like the "devil grass" in Stephen King's Dark Tower series.

[justshutupandtakeit]

That is close but the Assassins were the followers of a particular cult within Islam often considered heretical. The followers of Hassan Ibn Sabbah and the Old Man of the Mountains. Their favorite tactic was to infiltrate the Courts waiting to do their masters' bidding. Often they would wait for years acting the sober, efficient and faithful servant. They did not need hashish to do their deeds. It's use within the sect was more for brainwashing than to allow them to do their deeds.