Complex sentence: Around 1218 his father arranged his marriage with Princess Anna, daughter of King Ottokar I of Bohemia; this union with the royal Přemyslid dynasty allowed Henry II to participate actively in international politics.
Split into simpler sentences: Around 1218 his father arranged his marriage to Princess Anna, daughter of King Ottokar I of Bohemia. This union with the royal Přemyslid dynasty allowed Henry II to participate actively in international politics.