Complex sentence: Pope Pope Benedict XVI appointed Christopher Coyne to assist Buechlein with his duties in March 2011, and on September 21,2011, the Holy See granted Archbishop Buechlein an early retirement at the age of 73, due to health issues.
Split into simpler sentences: Pope Pope Benedict XVI appointed Christopher Coyne to assist Archbishop Buechlein with his duties in March 2011. On September 21,2011, the Holy See granted Archbishop Buechlein an early retirement at the age of 73, due to health issues.