Complex sentence: Woodham-Smith (1953: 240--250) Cambridge forwarded the letter to Cardigan for comment and Cardigan's reply in turn complained that Paget had not in fact taken his regiments into the attack.
Split into simpler sentences: Woodham-Smith (1953: 240--250) Cambridge forwarded the letter to Cardigan for comment. His letter in response in turn complained that Paget had not in fact taken his regiments into the attack.