Complex sentence: Princess Sophia Albertina of Sweden (full name: Sophia Maria Lovisa Fredrika Albertina; 8 October/18 October 1753--17 March 1829) reigned as Princess-Abbess of Quedlinburg Abbey and a vassal monarch of the Holy Roman Empire.
Split into simpler sentences: Princess Sophia Albertina of Sweden (full name: Sophia Maria Lovisa Fredrika Albertina; 8 October 1753--17 March 1829) was a Swedish Princess. She was a Princess-Abbess of Quedlinburg Abbey and as such reigned as vassal monarch of the Holy Roman Empire.