Rather like the Grand Old Duke of York, the Chief of Staff of the Army, Lieut Gen Dave Stapleton, will soon command a force of roughly 10,000 men if the White Paper proposals on the Defence Forces are implemented.

While one perception is that the Army has nothing much else to do but march up and down hills nursery rhyme-style, the Army boss is said to be intensely frustrated by the White Paper which proposes reducing numbers by 1,000. The 62-year-old is due to retire on his 63rd birthday in September but if the current crisis is not resolved, speculation that he may resign in protest at the cuts could see him go sooner than that.

Whether he opts for this potentially explosive course of action, his departure from the Army will end an illustrious 45-year career which friends and colleagues say has been carved using his two most distinctive qualities - steely determination and an unerring ability to plan.

Such was his concern about recent developments, he cut short a morale-boosting tour in East Timor where the elite Army Ranger wing is on UN duty.

A source close to the Army chief surmised that his frustration is based on a characteristically pragmatic point of view. "He is most likely thinking, `How on earth can I do this job?' He knows the demands that will be placed on the force in the future, not least in the inevitable intensifying of overseas activity, including the PfP and the Helsinki Accord. He cannot see how these demands can be met if the Department continues to pare down resources."

He is a strong individual with the highest calibre military education and experience, the source added, who has nothing more to prove. "If he doesn't think it can be done properly he will walk away."

The whispers around the barracks are that in the event of his resignation other Army top brass would be likely to follow his lead. Such speculation could be little more than a ploy designed to put pressure on the Minister for Defence, Mr Smith, who has already set up damage-limitation meetings between senior civil servants and top-ranking military management. However, Mr Smith also said this week that there was no room for manoeuvre on Army numbers.

The battle lines have been clearly drawn.

Lieut Gen Stapleton is not the kind of boss on whom a nickname would be bestowed - the closest military folk come to such familiarity is calling him Davy. He joined the Army in 1955, beginning his career as a member of the Supply and Transport Corps in the Curragh.

His ability marked him out early on for his rapid advance, an upward path which became more inevitable when, in 1977, he was chosen to attend a command and staff course in Camberley Military College, England. He followed this with five years as a lecturer in the Curragh military college.

He has vast overseas experience, serving with the UN in the Congo in 1962, Syria in 1972 and Lebanon in 1983 and 1985. While he was serving as a UNMO (UN military observer) in the Golan Heights in 1972, his family's apartment in Damascus was hit in an air strike and his wife, Maureen, suffered a bad eye injury.

A soldier who served with him in Namibia in 1989 during its transition to independence after South African occupation remembers when they were dispatched to Keetsmanshoep to set up a UN station. Lieut Gen Stapleton turned up to a community meeting only to be faced with 700 hostile locals deeply suspicious about the arrival of these uniformed white men.

"By the end of the meeting he had them eating out of his palm," recalls the soldier. "It was his calm, friendly disposition that guaranteed the UN a trouble-free run in the area."

He was subsequently made director of elections for Namibia's southern sector.

Having made it to the rank of quartermaster general, Lieut Gen Stapleton was appointed to the top job in September 1998, despite the fact that he was only two years away from retirement. A popular choice among politicians and civil servants, he was brought home early from his position as Force Commander of UNDOF (the UN Disengagement Observer Force) in the Golan Heights to take up the role.

His special relationship with the Army representative bodies - he was the first president of RACO, the Representative Association for Commissioned Officers - has been of benefit to him in his current appointment. (Both RACO and PDFORRA stand square behind him now.) His commitment to establishing these bodies was viewed as courageous because it involved clashing with senior military management, a course which could have been detrimental to his progress within the Army.

"He basically had to tell those senior to him that `the times they were a changin'," said one colleague. "It could have spelled the end of his career."

It didn't and throughout this period in the late 1980s and early 1990s he established and maintained excellent relations with many of the Department officials he has locked horns with in the past week.

A long-time friend, Lieut Gen Gerry McMahon, who preceded Lieut Gen Stapleton as Chief of Staff, describes him as "quiet and reserved - not a social mixer". "He is warm and open with his friends and those whom he trusts," he said.

His greatest love is Gaelic football and he was a player for his home county of Tipperary at all levels. He enjoys the occasional glass of wine, reading and gardening. He has three grown-up daughters and a son who is an ex-Army member.

"Over the past two years he has displayed an easy, open and approachable style and he has won the respect of personnel at all levels," said Lieut Gen McMahon, assessing his friend's term. "He has done much to sell the Defence Forces to the wider political arena."

His time as head of the force came when the Army's image was low. He has made concerted efforts to reverse the negative image fuelled by, most notably, the Army deafness claims.

What has surprised Army personnel most in recent days is that the Government did not consult the Defence Force's top strategist before deciding future policy. The submission made by Lieut Gen Stapleton for the White Paper was described by one insider as "reasonable" but his main contention, that force numbers remain unchanged, was not accepted.

"The whole force is shocked," said one source. "He has stood his ground during the current impasse despite very severe pressure and despite his views being ignored. He is a very angry man," said a close friend who acknowledges that resignation would have crossed Lieut Gen Stapleton's mind.

But whatever course of action he takes, said a colleague, it will be in the best interests of the Defence Forces. "His commitment to the force and the Irish people is unshakeable. And that commitment will be the main motivation in any decision he makes," he said.