Complex sentence: The sixth HMS "Monmouth" of the British Royal Navy was the name-ship of the "Monmouth" class of armoured cruiser of 9,800 tons displacement, sunk at the Battle of Coronel in 1914.
Split into simpler sentences: The sixth HMS "Monmouth" of the British Royal Navy was the name ship of the her class of armoured cruiser of 9,800 tons displacement. She was sunk at the Battle of Coronel in 1914.