Complex sentence: Bombes became the primary mechanical aid in breaking Enigma ciphers during the war, by speeding up the search for current wheel order settings being used with the Enigma machines; these were changed often, initially at least once per day.
Split into simpler sentences: Bombes became the primary mechanical aid in breaking Enigma ciphers during the war, by speeding up the search for current wheel order settings being used with the Enigma machines. Wheel order settings were changed often, initially at least once per day.