Complex sentence: He died on 21st May 1865 at Westminster Hospital, London from acute Myelitis (inflammation of the spinal cord) and asphyxia and was buried in a common grave at Brompton Cemetery, on which a memorial has now been placed.
Split into simpler sentences: He died on 21 May 1865 at Westminster Hospital, London from acute myelitis (inflammation of the spinal cord) and asphyxia. He was buried in a common grave in Brompton Cemetery, on which a memorial has now been placed.