The details of how Telemann obtained his next position are unknown. Around 1707–1708 he entered the service of Duke Johann Wilhelm of Saxe-Eisenach, becoming Konzertmeister on 24 December 1708 and Secretary and Kapellmeister in August 1709. Thus began one of the most productive periods in Telemann's life: during his tenure at Eisenach he composed a wealth of instrumental music (sonatas and concertos), and numerous sacred works, which included four or five complete annual cycles of church cantatas, 50 German and Italian cantatas, and some 20 serenatas. In 1709 he made a short trip to Sorau to marry Amalie Louise Juliane Eberlin, lady-in-waiting to the Countess of Promnitz and daughter of the musician Daniel Eberlin. They went back to Eisenach, where in January 1711 Amalie Louise gave birth to a daughter. Unfortunately, the mother died soon afterwards; Telemann's marriage lasted only for 15 months.