Complex sentence: At the age of 16 in 1982 he joined the Royal Irish Rangers which became the Royal Irish Regiment in 1992, and in over 28 years of service rose from the rank of "Ranger" to that of Regimental sergeant major.
Split into simpler sentences: At the age of 16 in 1982 he joined the Royal Irish Rangers which became the RIR in 1992. In over 28 years of service rose from the rank of "Ranger" to that of Regimental sergeant major.