Complex sentence: Many Napoleonic forts were built during the Napoleonic War in South East Cornwall to protect Plymouth Sound and Plymouth's docks in Devonport, Devon from attack: some are still in use today by the Ministry of Defence.
Split into simpler sentences: Many Napoleonic Forts were built during the Napoleonic War in South East Cornwall to protect Plymouth Sound and Plymouth's docks in Devonport, Devon from attack. Some are still in use today by the Ministry of Defence.