Simplify the following text for a Grade 11 native English-speaking person.
Original: The three sons of John Frederick I shared the territory , with John Frederick II becoming head ( and briefly , 1554-56 , holding the electoral title ) with his seats in Eisenach and Coburg , the middle brother John William staying in Weimar ( Saxe-Weimar ) , and the youngest , John Frederick III ( namesake of the eldest brother , which thing has caused innumerable confusion in history writing ) establishing residence in Gotha ( Saxe-Gotha ) . 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 II set up his capitals in in Eisenach and Coburg , the middle brother John William staying in Weimar ( Saxe-Weimar ) , and the youngest , John Frederick III took Gotha ( Saxe-Gotha ) .