Complex sentence: In 1991 he assumed command of 1st Battalion, Cheshire Regiment, and as commanding officer returned to Northern Ireland for a further two operational tours and then became the first British Commander of United Nations forces in Bosnia from September 1992 to May 1993.
Split into simpler sentences: In 1991 he assumed command of 1st Battalion, Cheshire Regiment, and as commanding officer returned to Northern Ireland for a further two operational tours. He then became the first British Commander of United Nations forces in Bosnia from September 1992 to May 1993.