Dom Nuno Alvares Pereira, as Constable of Portugal, ably assisted King Joao I not only became known as 'the Holy Constable', but was regarded as the model of knightly chivalry and perfection. He remained in the king's service for many years but finally retired to a monastry where he, as Brother Nuno de Santa Maria, died two years before the king.
 

Source: Leo van de Pas