Complex sentence: It was then rebuilt by Governor Sir Graham Briggs in the late 19th century, but because of the population decline on the island, the Cottle Church again fell into ruins at the turn of the 20th century.
Split into simpler sentences: It was then rebuilt by Governor Sir Graham Briggs in the late 19th century. But because of the population decline on the island, the Cottle Church again fell into ruins at the turn of the 20th century.