Complex sentence: Nevertheless, the 12-year-old Élisabeth was engaged by proxy on 26 August 1739, without having met her future husband, after which she was known as "Madame Infante".
Split into simpler sentences: Nevertheless, the young Élisabeth was engaged by proxy on 26 August, 1739, without having met her future husband. Afterwards, she was known as "Madame Infante".