The call to military life reached Colm Mangan at boyhood. A career in law or the Civil Service might have seemed likely for the son of Kevin Mangan, a lawyer in the Attorney General's office and later chief legal adviser to the Government.

However, as a boy the new Chief of Staff of the Defence Forces displayed signs that he was in need of the "disciplined" atmosphere of Rockwell College. The wrench from the comfort of a large and warm family in suburban south Dublin to boarding school in Tipperary appears to have had little impact and he thrived in the sporting and academic atmosphere of the college.

During his time there, he joined the cadet corps in the school and from that point, friends say, he was determined the Army would be his life. He applied for a cadetship at the same time as he applied for University College Dublin. When, after a few months in university, a place was offered on the officer cadet course he packed his bags and arrived in the Curragh in December 1961.

From the outset his career was with the infantry and particularly with the "Bloods", the 3rd Infantry Battalion in the Curragh. His career is inextricably connected with this tightly-bonded unit whose insignia of the Red Hand of Ulster gives them their nickname.

His first command in active service was three years later when, as a young lieutenant, he led a platoon with the UN peacekeeping force sent to establish the truce after the civil war in Cyprus. The unit had a difficult few weeks in Larnaka but was then sent west to the relative peace of the countryside around Pathos. There were no casualties.

After another tour of duty in Cyprus he volunteered for service as a military observer with the UN Truce Supervision Organisation (UNTSO) in the Middle East and managed to walk into one of the most intense battle sites in the 1973 Yom Kippur war. He and another young Norwegian officer were posted to an observation position - now famous in peacekeeping history - at the Rafid road junction on the Golan Heights.

They were just settling into their new position when Syria made its ill-fated invasion attempt on Israel. The Syrian tanks rolled past the post and three days later were driven back before a massive Israeli repulse. The UN post above ground was destroyed by shelling and bombing while the two young "observers" sheltered in an underground bunker. In a pause in the fighting, Mangan (59) and the Norwegian attempted to drive into Israel only to be caught in a Syrian convoy which was bombed and strafed by Israeli planes. They managed to escape unscathed.

Later in his career he worked again as a military observer with the Council for Security and Co-operation and was sent to Osijek, near Vukovar in eastern Croatia, during the Serbian bombardment of Croatian positions in 1991 and 1992. During his period in Osijek, the town was under constant shellfire.

On his return from the Middle East in 1974 he returned to the Curragh Command, continuing his career as an infantry officer. He played rugby for the Curragh and joined Galway Corinthians, winning a Connacht medal.

He also began what became a lifelong interest in amateur drama and the Irish language. He has appeared on many occasions with the Moat Club, from Naas, one of the country's better amateur dramatic societies. He has been a strong supporter of the Irish language and his three sons attended Irish-speaking national schools near their home in Newbridge. One of his sons, Cormac, is now a captain in the Cadet School. Another son, Colm, is at Trinity College and another is an accounts executive with a Dublin newspaper. Maj Gen Mangan still lives in Newbridge, where he settled with his wife, Margaret, when they married.

As a young officer he attended the Goethe Institute in Dublin and learned German. In 1977 he attended the Fuhrungs Akademie in Hamburg, where he completed the German army's general staff course - the course which sets young officers on the road to high command. He is still the only Defence Forces officer to have completed this course. During his time in Germany in 1977 and 1978 he served for a while with the German mountain infantry brigade, the Gebirgsjaeger, in Bavaria, a period he is said to remember as the most enjoyable experience of his military life.

The other high point in his military career, colleagues say, is his period as commanding officer of the 68th Irish Battalion in south Lebanon in 1990 and 1991.

His German and his contacts with colleagues in the German army will be a bonus in the coming years as the Republic moves, under the Amsterdam Treaty, to involvement in peacekeeping duties - the so-called Petersberg Tasks - ordained by the EU.

During the coming three years as head of the Defence Forces, Maj Gen Mangan (he adopts the title of lieutenant general on appoint in September) will oversee the early stages of committing Irish soldiers to service with the European Rapid Reaction Force.

It is anticipated that the Defence Forces will have to make a commitment of a mechanised infantry battalion, of between 700 and 1,000 troops, to the 60,000-strong force. Senior military figures close to him say he is excited at the prospect of commanding the newly-organised and equipped Defence Forces which he has already played a role in shaping.

He was responsible for the shaping of the Defence Forces' response to the review of its structure and organisation that led to the 1996 reorganisation plan. Key to the Army's demands were the provision of more and better equipment.

During most of his career the Army scraped by with a minimum of equipment. In the coming year it will receive the first shipment of 40 powerful Mowag armoured troop carriers, at a cost of more than £1 million each.

The move towards greater EU defence involvement will coincide with the diminution of the Defence Forces' peacekeeping role in the UN, marking a major policy change on behalf of Government. But this also reflects the reality that since the disastrous experiences of the UN in Somalia and then former Yugoslavia, the US and the major European military nations are unlikely ever again to heavily commit forces to any mission led by the UN.

As Chief of Staff he will have command of a force that will have to fulfil a real military role, integrated in a major European army. Colleagues in the military say Maj Gen Mangan has the background and strategic planning abilities to create the new professional Army.