With respect to Auden's language we can see here "the dreadful martyrdom must run its course" (the innocent boys of Herod's wrath are traditionally considered the first of the Christian martyrs).
Med Audens språk i beaktande kan vi här se "the dreadful martyrdom must run its course" (de oskyldiga pojkarna som faller offer för Herodes vrede ses traditionellt som de första kristna martyrerna.