Complex sentence: Elizabeth was to seduce her husband into confiding military secrets to her, military intelligence which the Hellfire Club would use to end the "pitiful" American Revolution and assure the victory of the Kingdom of Great Britain.
Split into simpler sentences: Elizabeth was to seduce her husband into confiding military secrets to her. Military intelligence which the Hellfire Club would use to end the "pitiful" American Revolution and assure the victory of the Kingdom of Great Britain.