Complex sentence: In 1907, his management skills led to his recruitment by the struggling UERL which he quickly helped recover from a financial crisis and then managed during the London Underground's greatest period of expansion between the two World Wars.
Split into simpler sentences: In 1907, his management skills led to his recruitment by the struggling UERL. He quickly helped it recover from a financial crisis and then managed it during the London Underground's greatest period of expansion between the two World Wars.