Original: When John Frederick III of Gotha died unmarried and heirless in 1565, John William of Weimar tried to claim succession to Saxe-Gotha, but the sons of the imprisoned John Frederick II entered their own claim.
Simplified: John Frederick III of Gotha died unmarried and heirless in 1565 and John William of Weimar tried to claim Saxe-Gotha, but the sons of the imprisoned John Frederick II entered their own claim.