Complex sentence: The "princesse de Lamballe" attended every royal ceremony, and was in 1770 presented to the new dauphine, who was charmed with Marie Thérèse, and overwhelmed her with attention and affection that spectators did not fail to notice.
Split into simpler sentences: The "princesse de Lamballe" attended every royal ceremony and, in 1770, was presented to the new dauphine. The Queen was charmed by Marie Thérèse, and overwhelmed her with attention and affection that spectators did not fail to notice.