Complex sentence: The 1st Battalion, 9th Marines (1/9) reactivated on April 18,2007, the 2nd Battalion reactivated in July 2007, and the 3rd Battalion reactivated in May 2008.
Split into simpler sentences: The 1st Battalion, 9th Marines (1/9) reactivated on April 18,2007. The 2nd Battalion reactivated in July 2007, while the 3rd Battalion reactivated in May 2008.