Two years later occurred the first important episode in Ewald's studious life. In 1837, on 18 November, along with six of his colleagues he signed a formal protest against the action of King Ernst August in abolishing the liberal constitution of 1833, which had been granted to the House of Hanover by his predecessor William IV. This procedure of the seven professors led to their expulsion from the university (14 December). Early in 1838 Ewald received a call to Tübingen, and there for upwards of ten years he held a chair as professor ordinarius, first in philosophy and afterwards, from 1841, in theology. To this period belong some of his most important works, and also the commencement of his bitter feud with F.C. Baur and the Tübingen school. In 1847, "the great shipwreck-year in Germany," as he has called it, he was invited back to Göttingen on honourable terms—the liberal constitution having been restored. He accepted the invitation.