From England a new ambassador was soon to take the place of Winwood. Sir Dudley Carleton was a diplomatist of respectable abilities, and well trained to business and routine. Perhaps on the whole there was none other, in that epoch of official mediocrity, more competent than he to fill what was then certainly the most important of foreign posts. His course of life had in no wise familiarized him with the intricacies of the Dutch constitution, nor could the diplomatic profession, combined with a long residence at Venice, be deemed especially favourable for deep studies of the mysteries of predestination. Yet he would be found ready at the bidding of his master to grapple with Grotius and Barneveld on the field of history and law, and thread with Uytenbogaert or Taurinus all the subtleties of Arminianism and Gomarism as if he had been half his life both a regular practitioner at the Supreme Court of the Hague and professor of theology at the University of Leyden. Whether the triumphs achieved in such encounters were substantial and due entirely to his own genius might be doubtful. At all events he had a sovereign behind him who was incapable of making a mistake on any subject. "You shall not forget," said James in his instructions to Sir Dudley, "that you are the minister of that master whom God hath made the sole protector of his religion . . . . . and you may let fall how hateful the maintaining of erroneous opinions is to the majesty of God and how displeasing to us." The warlike operations of 1614 had been ended by the abortive peace of Xanten. The two rival pretenders to the duchies were to halve the territory, drawing lots for the first choice, all foreign troops were to be withdrawn, and a pledge was to be given that no fortress should be placed in the hands of any power. But Spain at the last moment had refused to sanction the treaty, and everything was remitted to what might be exactly described as a state of sixes and sevens. Subsequently it was hoped that the States' troops might be induced to withdraw simultaneously with the Catholic forces on an undertaking by Spinola that there should be no re-occupation of the disputed territory either by the Republic or by Spain. But Barneveld accurately pointed out that, although the Marquis was a splendid commander and, so long as he was at the head of the armies, a most powerful potentate, he might be superseded at any moment. Count Bucquoy, for example, might suddenly appear in his place and refuse to be bound by any military arrangement of his predecessor. Then the Archduke proposed to give a guarantee that in case of a mutual withdrawal there should be no return of the troops, no recapture of garrisons. But Barneveld, speaking for the States, liked not the security. The Archduke was but the puppet of Spain, and Spain had no part in the guarantee. She held the strings, and might cause him at any moment to play what pranks she chose.