In Germany, on the other hand, an entirely different policy was pursued. The concessions granted by Frederick in 1220, together with the Privilege of Worms, dated the 1st of May 1231, made the German princes virtually independent. All jurisdiction over their lands was vested in them, no new mints or toll-centres were to be erected on their domains, and the imperial authority was restricted to a small and dwindling area. A fierce attack was also made on the rights of the cities. Compelled to restore all their lands, their jurisdiction was bounded by their city-walls; they were forbidden to receive the dependents of the princes; all trade gilds were declared abolished; and all official appointments made without the consent of the archbishop or bishop were annulled. A further attack on the Lombard cities at the diet of Ravenna in 1231 was answered by a renewal of their league, and was soon connected with unrest in Germany. About 1231 a breach took place between Frederick and his elder son Henry, who appears to have opposed the Privilege of Worms and to have favoured the towns against the princes. After refusing to travel to Italy, Henry changed his mind and submitted to his father at Aquileia in 1232; and a temporary peace was made with the Lombard cities in June 1233. But on his return to Germany Henry again raised the standard of revolt, and made a league with the Lombards in December 1234. Frederick, meanwhile, having helped Pope Gregory against the rebellious Romans and having secured the friendship of France and England, appeared in Germany early in 1235 and put down this rising without difficulty. Henry was imprisoned, but his associates were treated leniently. In August 1235 a splendid diet was held at Mainz, during which the marriage of the emperor with Isabella (1214-1241), daughter of John, king of England, was celebrated. A general peace (_Landfrieden_), which became the basis of all such peaces in the future, was sworn to; a new office, that of imperial justiciar, was created, and a permanent judicial record was first instituted. Otto of Brunswick, grandson of Henry the Lion, duke of Saxony, was made duke of Brunswick-Lueneburg; and war was declared against the Lombards.