The Elector of Hesse-Cassel, unmoved even by a monster petition headed with the name of Lord Aberdeen, declined to permit Spohr to go to England, and conduct the "Fall of Babylon" at the Norwich Festival. The oratorio was produced without his assistance and was highly successful. He went to England, however, at the beginning of his summer vacation and gave some profitable concerts. In 1844 he brought forward his last opera, "Die Kreuzfahrer" ("The Crusaders"). For this he had arranged his own libretto from a play by Kotzebue. The success of the opera, performed at Cassel and Berlin, was brief. He made a trip to Paris, where the Conservatoire orchestra honored him with a special performance of his "Consecration of Tones." He conducted the "Missa Solemnis" and the Ninth Symphony at the Beethoven Festival at Bonn, in the same year. In 1847 he again visited London, when his "Fall of Babylon," "Last Judgment," "Lord's Prayer," and Milton's eighty-fourth psalm were presented in three concerts by the Sacred Harmonic Society. In the same year the twenty-fifth anniversary of his assumption of the directorship at Cassel was celebrated by a performance of excerpts from his operas. The revolutionary events of 1848 interrupted Spohr's flow of compositions. He felt, as he wrote to his friend Hauptmann, that "the excitement of politics and the constant reading of newspapers incapacitated him from giving his attention to any serious and quiet study." In 1849, while recovering from an illness caused by a fall on the ice, he planned his ninth symphony, "The Seasons," which he wrote shortly after his recovery. He went to Breslau in the hope of hearing Schumann's "Genoveva," but owing to delays heard only some rehearsals. During his two weeks' stay in Breslau, honors were heaped upon him. Banquets were given, concerts of his music were arranged, and his opera "Zemire und Azor" was performed at the theatre. In 1850 he was made to suffer from court malice. The Elector, probably to chastise him for his radical political ideas, refused him permission to take a summer vacation. He went away without leave, and the result was a lawsuit with the managers of the theatre, which after four years he lost by a technicality.