By this treaty the duke of Nevers was invested with the duchy, and the fortresses were restored on both sides, except Pinerolo, which was still held by the French. So ended the first great effort made by Richelieu against the House of Habsburg. Like most of his plans it was better conceived than executed, but it must be remembered that in carrying it out, he was sorely hampered by opposition to his authority at home both from the Huguenots and from the nobles. His Italian policy must not be considered by itself. It is part of a great whole. While he was openly attacking the imperial forces in Italy, his diplomacy was undermining the imperialist power in Germany, and if in 1631 he thought it best to rest content with the reduction of Savoy, and the acquisition of a passage through the Alps, it was because at that particular moment he could best effect his purpose by shifting his method from direct to indirect hostility, and the scene from Italy to Germany. [Sidenote: =Intrigues of Richelieu in Germany, 1630.=] Already he had endeavoured to keep the flame of opposition to Spain alive by granting subsidies to the Dutch, and directing Mansfeld’s army in 1624 to the Netherlands. In July 1630, he sent his most trusted agent the famous Capuchin, Father Joseph, to the meeting of the diet of Regensburg, where he laboured with notable skill and success to bring about the dismissal of Wallenstein, and to pave the way for detaching Maximilian of Bavaria and the League from their close alliance with the Emperor and Spain. In the autumn of the year before, another well-trained diplomatist, Charnacé, had travelled as far as Dantzig to offer the mediation of France in the quarrel between Sweden and Poland, and so removed one of the obstacles which made Gustavus Adolphus hesitate to take part in the German War. At that time Richelieu seems to have thought that he could use Gustavus merely as a fighting tool, and by offering him French money and a French alliance could make him fight the battles of France against the Emperor. But he was quickly undeceived. Gustavus definitely refused to allow his political or military independence to be impaired. He was quite willing that France should interfere openly in the war, if she chose to do so, provided she would limit her operations to the left bank of the Rhine; but he would not tolerate for a moment any interference with his own command. The utmost that Richelieu could obtain from him by the treaty of Bärwalde in 1631, in return for French gold, was the promise to observe friendship or neutrality towards Bavaria and the League, so far as they would observe them towards him. Nor was this promise of much avail, for when, after the battle of Breitenfeld, Gustavus determined to march upon central and southern Germany instead of on Vienna, all hope of detaching Bavaria from the Emperor had to be laid aside. [Sidenote: =Open interference in Germany, 1632–1634.=]