Just as the lot had been thus decided, the conspirators were startled by the sound of a cannon shot repeated three times from the fortress of the city; and this being the signal for Don Carlos, he stepped forth from the mausoleum with a stern and regal air. At the same moment there entered from another door six Electors and the Ministers of State, followed by royal pages who bore the crown and regalia; and after these came a retinue of splendidly dressed lords and ladies, amongst whom was the pale and drooping Elvira.
At the bidding of the Electors the crown was placed upon the head of the young King, and he was solemnly hailed as the Sovereign; and Carlos, with equally dignified solemnity, accepted the charge laid upon him. Then, turning to the discomfited conspirators, he exposed their plot; and, denouncing them as traitors, he condemned the nobles to the block and the plebeians to prison. Ernani was herded with the latter; but refusing to bear such an insult, he now disclosed his true identity as a Duke of ancient family, and haughtily claimed the death of an aristocrat.
Carlos readily granted this plea; but Elvira, in despair at thus losing her lover for ever, fell on her knees, and passionately implored the King to pardon Ernani, adding as her plea, "Virtue sublime is mercy in kings!"
As Carlos listened to the pleading voice of the beautiful Elvira, he was reminded of the sacred vow he had so recently made; and, desiring to win the affection of his people by ruling them with love and clemency, he now magnanimously proclaimed a gracious pardon for all the conspirators. Further than this, he steadfastly quelled the longings of his youthful heart, and resigned all further thoughts of Elvira; and knowing that her love was given to Ernani, he declared it to be his royal will that the pair should be united.
So the faithful lovers were wedded at last; and Ernani and his fair bride retired to the ex-bandit's ducal palace, where a noble company had assembled to bid them welcome and join in the bridal festivities. But amongst the merry company of wedding guests there glided a masked stranger, who greeted no one, and held himself aloof from all; and this was none other than Don Silva, who, less noble than his King, was consumed with fierce jealousy at the happiness of his favoured rival, and had now come to indulge in a cruel vengeance.
When the guests had departed, and Ernani and his bride were alone, they embraced each other with great joy, thankful that their troubles were over, and wondering at the unexpected happiness which lay before them; but suddenly they were startled by the loud lingering blast of a hunting-horn.
Ernani became pale as death, and his heart stiffened with horror; for he remembered his vow to Don Silva, and knew that this was the signal for him to die. Elvira was filled with alarm at his altered looks; but Ernani declared that he was unwell, and bade her fetch him a cordial, that in her absence he might brace himself for his fearful act. Full of grief that his cup of happiness should be thus snatched from him as he was about to enjoy it, he thought wildly for a moment of escape; but just as he was about to follow Elvira, Don Silva himself entered the room, and calmly bade him fulfil the solemn promise he had made, adding, with fiendish triumph, that one so nobly born and of such high character could not stoop to forswear himself.
Well did Ernani know this; for never yet had he broken his word to any living soul, nor could his high sense of honour permit him to do so now. Just as he drew his dagger, however, Elvira returned to the room; and now hearing of the fearful compact which had been made between the two rivals for her hand, she knelt before Don Silva and besought him, with distracted sobs, to release her beloved husband from his vow.
But Don Silva had steeled his heart to withstand this piteous appeal, and coldly announced that he awaited the fulfilment of his rival's vow; and Ernani, knowing well that he could expect no mercy from such a remorseless foe, and too proud to tarnish his honourable name by forswearing himself, clasped the weeping Elvira in a last embrace. Then quickly grasping his dagger he resolutely stabbed himself to the heart, faithful to the fatal promise he had made; and as Elvira, with a terrible cry of woe, fell senseless beside him, he expired and Don Silva's vengeance was accomplished.