Complex sentence: He returned to Washington to serve briefly on a board reviewing naval promotions, and then while on a trip to Philadelphia with his wife, he died on June 23,1865, without being officially exonerated.
Split into simpler sentences: He returned to Washington to serve briefly on a board reviewing naval promotions. Du Pont died on June 23,1865 while on a trip to Philadelphia with his wife, he died on June 23,1865, without being officially exonerated.