Daniel Goldhagen points out in Hitler's Willing Executioners (pp. 149-50) how the"up-close," intimate killing of manifestly defenceless, screaming civilians on the eastern front -- killings which spattered blood and brain matter around the killing fields and over the killers -- was at first incrementally managed according to gender:
The Einsatzgruppen [death-squad] officers ... could habituate their men into their new vocation as genocidal executioners through a stepwise escalation of the killing. First, by shooting primarily teenage and adult Jewish males, they would be able to acclimate themselves to mass executions without the shock of killing women, young children, and the infirm. According to Alfred Filbert, the commander of Einsatzkommando 9, the [execution] order from [Reinhard] Heydrich "quite clearly" "included also women and children." Yet, "in the first instance, without a doubt, the executions were limited generally to Jewish males." By generally keeping units' initial massacres to smallish numbers (by German standards) of a