Complex sentence: Between the wars, he was retained in the "Reichswehr", serving mostly with the 2nd Pioneer Battalion, before becoming an instructor at the Military Academy in August 1935 and he had a military textbook entitled "Service with the Pioneers" published in 1937.
Split into simpler sentences: Between the wars, he was retained in the "Reichswehr", serving mostly with the 2nd Pioneer Battalion, before becoming an instructor at the Military Academy in August 1935. He had a military textbook entitled "Service with the Pioneers" published in 1937.