Complex sentence: Southsea Common is a large expanse of mown grassland parallel to the shore from Clarence Pier to Southsea Castle, which owes its existence to the demands of the military for a clear range of fire from the harbour defences at enemy ships.
Split into simpler sentences: Southsea Common is a large expanse of mown grassland parallel to the shore from Clarence Pier to Southsea Castle. The Common owes its existence to the demands of the military for a clear range of fire from the harbour defences at enemy ships.