Complex sentence: The small town of Winterthur lies north east of Zürich, in Switzerland, at the junction of seven cross-roads; the army that held the town held the access to most of Switzerland and points crossing the Rhine into southern Germany.
Split into simpler sentences: The small town of Winterthur lies north east of Zürich, in Switzerland. Because of its position at the junction of seven cross-roads, the army that held the town held the access to most of Switzerland and points crossing the Rhine into southern Germany.