Complex sentence: At the end of 1943, he was promoted to Untersturmführer and in April 1944 was a platoon leader in the 1st Company, 502nd SS Jäger Battalion "Mitte".
Split into simpler sentences: At the end of 1943, he was promoted to Untersturmführer. In April 1944, he became a platoon leader in the 1st Company, 502nd SS Jäger Battalion of SS-Jagdverband "Mitte".