Pope Innocent III. died in 1216, and Frederick appears to have considered that the assistance which he had received from him was _personal_ and not _Papal_; for he not only laid claim to the Tuscan possessions, but neglected his promise to engage in a new Crusade for the recovery of Jerusalem, and even attempted to control the choice of Bishops. At the same time he took measures to secure the coronation of his infant son, Henry, as his successor. His journey to Rome was made in the year 1220. The new Pope, Honorius III., a man of a mild and yielding nature, nevertheless only crowned him on condition that he would observe the violated claims of the Church, and especially that he would strictly suppress all heresy in the Empire. When he had been crowned Emperor as Frederick II., he fixed himself in Southern Italy and Sicily for some years, quite neglecting his German rule, but wisely improving the condition of his favorite kingdom. He was signally successful in controlling the Saracens, whose language he spoke, whom he converted into subjects, and who afterwards became his best soldiers. The Pope, however, became very impatient at the non-fulfilment of Frederick's promises, and the latter was compelled, in 1226, to summon a Diet of all the German and Italian princes to meet at Verona, in order to make preparations for a new crusade. But the cities of Lombardy, fearing that the army to be raised would be used against them, adopted all possible measures against the meeting of the Diet, took possession of the passes of the Adige, and prevented the Emperor's son, the young king Henry of Germany, and his followers, from entering Italy. Angry and humiliated, Frederick was compelled to return to Sicily. The next year, 1227, Honorius died, and the Cardinals elected as his successor Gregory IX., a man more than eighty years old, but of a remarkably stubborn and despotic nature. He immediately threatened the Emperor with excommunication in case the crusade for the recovery of Jerusalem was not at once undertaken, and the latter was compelled to obey. He hastily collected an army and fleet, and departed from Naples, but returned at the end of three days, alleging a serious illness as the cause of his sudden change of plan. [Sidenote: 1228. VISIT TO JERUSALEM.]