Complex sentence: He completed the "Realgymnasium" in 1918, afterwards he volunteered for the German Army and joined the "Anhaltische Infanterie-Regiment 93" as a Fahnenjunker.
Split into simpler sentences: He completed the "Realgymnasium" in 1918. Afterwards, he volunteered for the German Army and joined the "Anhaltische Infanterie-Regiment 93" as a Fahnenjunker.