Complex sentence: Arriving at an important crossing point at the town of Rheinfelden, Bernhard prepared to invest the town from the south and using the ferry at Beuggen threw troops across the river in order to complete the investment from the north.
Split into simpler sentences: Arriving at an important crossing point at the town of Rheinfelden, Bernhard prepared to invest the town from the south. Meanwhile, he would use the ferry at Beuggen to throw troops across the river in order to complete the investment from the north.