The power of kinship led to a common arrangement whereby extended families have protected themselves by sending one son to fight with the government army or police (for pay) and another son to fight with the Taliban. This has been a strategy in many civil wars, for example, among English noble families in the 15th-century Wars of the Roses. It means that at a given point, one of the sons can desert and return home without fearing persecution by the winning side.

These arrangements also serve practical purposes. It is often not possible for guerrilla forces to hold any significant number of prisoners of war. Small numbers might be held for ransom, but most ordinary soldiers are let go, enlisted in the guerrillas’ own ranks or killed.

Thus, as in medieval Europe, Afghanistan has a tradition to which the Taliban have adhered closely — and which helps explain the speed of their success. The Taliban will summon an enemy garrison to surrender, either at once or after the first assaults. If it does so, the men can either join the besiegers or return home with their personal weapons. To kill them would be seen as shameful. On the other hand, a garrison that fought it out could expect no quarter, a very strong incentive to surrender in good time.