Complex sentence: He then went briefly back into club management with German club Borussia Mönchengladbach, however he resigned on 18 April 2005 after less than six months at the helm.
Split into simpler sentences: He then went briefly back into club management with German club Borussia Mönchengladbach. He resigned, however, on 18 April 2005 after less than six months at the helm.