Complex sentence: He was promoted to detective Garda in July 1958 and Garda sergeant in December 1963 and put in charge of a mobile riot squad unit, which he remained active with until his retirement.
Split into simpler sentences: He was promoted to detective Garda in July 1958. James was promoted to Garda sergeant in December 1963 and put in charge of a mobile riot squad unit, which he remained active with until his retirement.