Melanchthon (1497-1560) was Luther's main collaborator. Whereas Luther considered himself the “rough pioneer who must break the road,” he credited Melanchthon with coming along softly and gently, sowing and watering heartily. His greatest contribution was the composition of the Augsburg Confession, the primary confession of faith of the Lutheran Church. It was presented at the Diet of Augsburg in 1530. The Diet had been called by the emperor, Charles V, in an effort to achieve religious and political unity against the Ottoman threat. The Diet failed in that regard but the Lutheran rulers agreed to a military alliance in the event of action by Charles.