Complex sentence: His letters to his sister, the princess of Holstein, preserved at Strassburg, were destroyed by the bombardment of that place in 1870; thirty copies had, however, been printed from the original.
Split into simpler sentences: His letters to his sister, the Princess of Holstein, preserved at Strassburg, were destroyed by the bombardment of that place in 1870. Thirty copies had, however, been printed from the original.