Complex sentence: Bishop Asser claimed that the'pagans' agreed to vacate the realm and made good their promise; and, indeed, the Viking army did withdraw from Reading in the autumn of 871 to take up winter quarters in Mercian London.
Split into simpler sentences: Bishop Asser claimed that the'pagans' agreed to vacate the realm and made good their promise. Indeed, the Viking army did withdraw from Reading in the autumn of 871 to take up winter quarters in Mercian London.