Complex sentence: The Special Air Service traces its origins to 1941 and World War II, it was reformed as part of the Territorial Army in 1947, named the "21st Special Air Service Regiment (Artists Rifles)".
Split into simpler sentences: The Special Air Service traces its origins to 1941 and the Second World War. It was reformed as part of the Territorial Army in 1947, named the "21st Special Air Service Regiment (Artists Rifles)".