Complex sentence: The WU Combined Chiefs of Staff Committee included observers from the United States which was initially led by Major General Lyman L. Lemnitzer, U.S. Army, and subsequently by Major General Franklin A. Kibler, USA.
Split into simpler sentences: The WU Combined Chiefs of Staff Committee included observers from the United States. It was initially led by Major General Lyman L. Lemnitzer, U.S. Army, and subsequently by Major General Franklin A. Kibler, USA.