 Complete the following phrase:  In 1915 Grüber was conscripted as a soldier and fought in World War I until 1918. In early 1918 he started an education as a military chaplain and in mid-1918 he passed the second state examination in theology and was accepted into the preacher seminary Domkandidatenstift at Berlins Supreme Parish and Collegiate Church. He was tutored by court preacher Bruno Doehring. In 1920 he was ordained as pastor in Berlin and took his first ministry in , Dortmund. In June 1923 the French occupation forces prompted Grübers expulsion from their 