Who is Lord Cardigan from Flashman at the Charge and what is their importance?

Lord Cardigan, who is a genuine historical figure, and the leader of the Light Brigade. Flashman and Cardigan do not get along, as Cardigan made inapproriate advances toward Flashman's wife, Elspeth. Although, Flashy and Elspeth have an open marriage, he does not appreciate having his wife's sexual escapades thrown in his face. Cardigan miraculously survives the Charge of the Light Brigade,