These "great companies," as they were called, exceeded 50,000 men in number, and as almost all were trained soldiers they set the king and his nobles at defiance, and were virtually masters of France. The most tempting offers were made to them to lay down their arms, and the pope sent legates threatening excommunication, but the great companies laughed alike at promises and threats. At last a way of deliverance opened to France. Pedro, named the Cruel, of Castile, had alienated his people by his cruelty, and had defeated and driven into exile his half-brother, Henry of Trastamare, who headed an insurrection against him. Pedro put to death numbers of the nobles of Castile, despoiled the King of Arragon, who had given aid to his brother, plundered and insulted the clergy, and allied himself with the Moors.

His quarrel with the clergy was the cause of his ruin. The pope summoned him to appear before him at Avignon to answer to the crimes laid to his charge. Pedro refused to attend, and the pope at once excommunicated him. The King of Arragon and Henry of Trastamare were then summoned to Avignon, and a treaty of alliance was concluded between them, and the pope declared the throne of Castile vacant owing to the excommunication of Pedro, and appointed Henry to it.