Complex sentence: He married his second wife, Princess Ulrika Eleonora of Sweden, in 1715 and served as prince consort of Sweden during Ulrika Eleonora's rule as Queen regnant from 1718 until her abdication in 1720, when he succeeded her on the throne.
Split into simpler sentences: He married his second wife, Princess Ulrika Eleonora of Sweden, in 1715. He served as prince consort of Sweden during Ulrika Eleonora's rule as Queen regnant from 1718 until her abdication in 1720, when he succeeded her on the throne.