 According to Njal 's saga , Bróðir tried by sorcery to predict the outcome of the battle against Brian . He <unk> that if the battle were on Good Friday , King Brian would fall but win the battle ; but if they fought on any day before , all who opposed Brian would be killed . Brian was unwilling to fight on Good Friday , as he would not fight on a fast day , but the Danes forced the battle to the Friday , which fell that year on 23 April . 
