Complex sentence: Victoria Josefa Dolores Catalina Sackville-West, Baroness Sackville (23 September 1862--30 January 1936) was the wife of her cousin Lionel Edward Sackville-West, 3rd Baron Sackville and mother of the writer, poet and gardener Vita Sackville-West.
Split into simpler sentences: Victoria Josefa Dolores Catalina Sackville-West, Baroness Sackville (23 September 1862--30 January 1936) married her cousin Lionel Edward Sackville-West, 3rd Baron Sackville. Their daughter was the writer, poet and gardener Vita Sackville-West.