Complex sentence: He grew up in Recklinghausen where he graduated from the local gymnasium and then served in the military from 1967 to 1971 after which he studied Economics at the University of Bonn, earning his doctorate.
Split into simpler sentences: He grew up in Recklinghausen where he graduated from the local gymnasium and then served in the military from 1967 to 1971. Thereafter he studied Economics at the University of Bonn, earning his doctorate.