Complex sentence: John Borland "Jack" Thayer III (December 24,1894-September 20,1945) was an American first-class passenger on the RMS "Titanic" from Philadelphia who provided several first-hand accounts of the disaster.
Split into simpler sentences: John Borland "Jack" Thayer III (December 24,1894-September 20,1945) was from Philadelphia. He was a first-class passenger on the RMS "Titanic" who provided several first-hand accounts of the disaster.