Complex sentence: After working up was completed early November 1940, "Dido" became a member of the 15th cruiser squadron, deployed in blockading the approaches to the Bay of Biscay, it was designed prevent raids by the German heavy cruiser Admiral Scheer.
Split into simpler sentences: After working up was completed early November 1940, "Dido" became a member of the 15th cruiser squadron deployed in blockading the approaches to the Bay of Biscay. This duty was designed to prevent raids by the German heavy cruiser Admiral Scheer.