Complex sentence: His cousin, King Christian III of Denmark, son of Frederick I, died in early 1559, and it was said that even then, with the old king nearing 80, people in Copenhagen looked warily towards Kalundborg.
Split into simpler sentences: His cousin, King Christian III of Denmark, Frederick I's son, died in early 1559. Even then, with the old king nearing 80, people in Copenhagen looked warily towards Kalundborg.