Complex sentence: But Julius III (Monte) had died in 1555, as had Marcellus II (Cervini); the Emperor Charles V had retired in 1556 and died in 1558; and both Paul IV and Henri II died in 1559, within a month of each other.
Split into simpler sentences: But Julius III (Monte) had died in 1555, as had Marcellus II (Cervini). The Emperor Charles V had retired in 1556 and died in 1558 and both Paul IV and Henri II died in 1559, within a month of each other.