Complex sentence: The Duchy came to an end in 1918 with the other German monarchies, and the Free State of Saxe-Coburg-Gotha was merged into the new state of Thuringia two years later.
Split into simpler sentences: The Duchy came to an end in 1918 with the other German monarchies, and the Free State of Saxe-Coburg-Gotha was established. This was merged into the new state of Thuringia two years later.