Complex sentence: He married Margaretta Lammot du Pont, the sister of company president Pierre S. du Pont, on December 18,1906, and began working under another brother, Irénée du Pont in the development department, of which he was named director in 1911.
Split into simpler sentences: He married Margaretta Lammot du Pont, the sister of company president Pierre S. du Pont, on December 18,1906. He began working under another brother, Irénée du Pont in the development department, of which he was named director in 1911.