This alarming claim of the earl's struck both the king and Buckingham with terror; and to prevent, if possible, the menaced charge, the Attorney-General was instantly despatched to the Lords to prefer a plea of high treason against Bristol. But the Peers were not thus to be circumvented. They replied that Bristol's accusation was first laid and must be first heard; and that without the counter-charge being held to prejudice his testimony. Bristol, thus at liberty to speak out, proceeded to town and to the House of Peers in triumph, his coach drawn by eight horses, caparisoned in cloth of gold or tissue; and Buckingham, as if to present a contrast of modesty, a quality wholly alien to his nature, drove thither in an old carriage with only three footmen and no retinue.

Bristol charged him with having concerted with Gondomar to inveigle the Prince of Wales into Spain, in order to procure his conversion to Popery prior to his marriage with the Infanta; with having complied with Popish ceremonies himself; with having, whilst at Madrid, disgraced the king, his country, and himself, by his contempt of all decency and the vileness of his profligacy. He stated that "As for the scandal given by his behaviour, as also his employing his power with the King of Spain for the procuring of favours and offices, which he conferred on base and unworthy persons, for the recompense and hire of his lust—these things, as neither fit for the Earl of Bristol to speak, nor, indeed, for the House to hear, he leaveth to your lordships' wisdoms how far it will please you to have them examined." He went on to charge him with breaking off the treaty of marriage solely through resentment, because the Spanish ministers, disgusted with his conduct, refused any negotiation with so infamous a person; and declared that, on his return, he had deceived both king and Parliament by a most false statement. All this the earl pledged himself to prove by written documents and other most undeniable evidence.

Instead of Buckingham attempting to clear himself as an innocent man so blackened by terrible charges would, it was sought to deprive the testimony of Bristol of all value by making him a criminal and a traitor to the king whilst his representative in Spain. Charles went so far as to send the Lord Keeper Coventry, a most pliant courtier, to inform the Lords that he would of his own knowledge clear the duke, the duke himself reserving his defence till after the impeachment by the Commons. Charles not only guaranteed to vindicate Buckingham, but accused Bristol of making a direct charge against himself, inasmuch as he himself had been with Buckingham all the time in Spain, and had verified his narrative on his return. The Peers passed this royal charge courageously by; and Charles then ordered the cause between Bristol and Buckingham to be removed from the Peers to the court of King's Bench; but the Lords would not permit such an infringement of their privileges. They put these questions themselves to the judges—"Whether the king could be a witness in a case of treason? And whether, in Bristol's case, he could be a witness at all, admitting the treason done with his privity?" The king sent the judges an order not to answer these questions, and in the midst of these proceedings the charges against Bristol were heard, and answered by him with a spirit and clearness which were perfectly satisfactory to the House. The charges against him amounted to this:—That he had falsely assured James of the sincerity of the Spanish Cabinet; had concurred in a plan for inducing the prince to change his religion; that he had endeavoured to force the marriage on Charles by delivering the procuration; and had given the lie to his present sovereign by declaring false what he had vouched in Buckingham's statement to be true. These were so palpably untenable positions that the House ordered Bristol's answer to be entered on the journals, and there left the matter.

But now the impeachment of Buckingham by the Commons was brought up to the Lords. It consisted of thirteen articles; the principal of which were that he had not only enriched himself with several of the highest offices of the State which had never before been held by one and the same person, but had purchased for money those of High Admiral and Warden of the Cinque Ports; that he had in those offices neglected the trade and the security of the coasts of the country; that he had perverted to his own use the revenues of the Crown; had filled the Court and dignities of the land with his poor relations; had put a squadron of English ships into the hands of the French, and on the other hand, by detaining for his own use a vessel belonging to the King of France, had provoked him to make reprisals on British merchants; that he had extorted ten thousand pounds from the East India Company; and even charged him with being accessory to the late king's death, by administering medicine contrary to the advice of the royal physicians.

Eight Managers were appointed by the Commons to conduct the impeachment—Sir Dudley Digges, Sir John Eliot, Serjeant Glanville, Selden, Whitelock, Pym, Herbert, and Wandsford. Digges opened the case, and was followed by Glanville, Selden, and Pym. While these gentlemen were speaking and detailing the main charges against him, Buckingham, confident in the power and will of the king to protect him, displayed the most impudent recklessness, laughing and jesting at the orators and their arguments. Serjeant Glanville, on one occasion, turned brusquely on him, and exclaimed, "My lord, do you jeer at me? Are these things to be jeered at? My lord, I can show you when a man of a greater blood than your lordship, as high in place and power, and as deep in the favour of the king as you, hath been hanged for as small a crime as the least of these articles contain."

Sir John Eliot wound up the charge, and compared Buckingham to Sejanus; as proud, insolent, rapacious, an accuser of others, a base adulator and tyrant by turns, and one who conferred commands and offices on his dependants. "Ask England, Scotland, and Ireland," exclaimed Sir John, "and they will tell you whether this man doth not the like. Sejanus's pride was so excessive, as Tacitus saith, that he neglected all counsel, mixed his business and service with the prince, and was often styled Imperatoris laborum socius. My lords," he said, "I have done. You see the man: by him came all evils; in him we find the cause; on him we expect the remedies."

The direct inference that if Buckingham was a Sejanus the king was a Tiberius, and a rumour that Eliot and Digges had hinted that in the death of the late king there was a greater than Buckingham behind, transported Charles with rage, and urged him on to another of those acts of aggression which ultimately brought him to actual battle with his Parliament. He had the two offending members called out of the House as if the king required their presence, when they were seized and sent to the Tower. This outrage on the persons of their fellow members and delegated prosecutors came like a thunder-clap on the House. There was instantly a vehement cry of "Rise! rise! rise!" The House was in a state of the highest ferment.

Charles hurried to the House of Lords to denounce the imputations cast upon him, and to defend Buckingham; and Buckingham stood by his side whilst he spoke. He declared that he had punished some insolent speeches, and that it was high time, for that he had been too lenient. He would give his evidence to clear Buckingham, he said, in every one of the articles, and he would suffer no one with impunity to charge himself with having any concern in the death of his father. But all this bravado was wasted on the Commons: again with closed doors they discussed the violation of their privileges, and resolved to proceed with no further business till their members should be discharged. In a few days this was done, and the House passed a resolution that the two members had only fulfilled their bounden duty.

On the 8th of June, Buckingham opened his defence in the House of Lords. In this he had been assisted by Sir Nicholas Hyde. He divided the charges against him into three classes: such as were unfounded in fact; such as might be true, but did not affect him; and lastly, those in which he had merely been the servant of the king or of the Executive. In all the circumstances which could be proved, he simply acted in obedience to the late or the present king, with one exception, the purchase of the office of Warden of the Cinque Ports, which he admitted that he had bought, but which he thought might be excused on the ground of public utility. As to the grave charge of the delivery of the king's ships to the French admiral, he did not mean to go into it, not but that he could prove his own innocence in the affair, but that he was bound not to reveal the secrets of the State; and he pleaded a pardon which had been granted by the king on the 10th of February, that is, four days after the opening of the present Parliament.