Complex sentence: At the beginning of 1848, Denmark included the Duchy of Schleswig, and the king of Denmark ruled the duchies of Holstein and Saxe-Lauenburg within the German Confederation, where the majority of the ethnic Germans in Denmark lived.
Split into simpler sentences: At the beginning of 1848, Denmark included the Duchy of Schleswig, and the king of Denmark ruled the duchies of Holstein and Saxe-Lauenburg within the German Confederation. Here the majority of the ethnic Germans in Denmark lived.