Complex sentence: In July 1957, a defence review was announced the result of which was that the North Staffords were to amalgamate with The South Staffordshire Regiment, and to become part of the new administrative Mercian Brigade.
Split into simpler sentences: In July 1957, a defence review was announced. The North Staffords were to amalgamate with The South Staffordshire Regiment, and to become part of the new administrative Mercian Brigade.