The Army luckily, never saw a military solution of the 'Troubles'.
Sent to prevent the province descending into anarchy, it was the Nationalist community they first protected.
However, one crucial mistake the government made, was not bringing in direct rule from London, when the troops were deployed or soon after.
If the N.I. government had, largely through their mis-deeds, like outright discrimination, gerrymandering, having a very partial police, especially the reserves, so that troops, unprecedented in modern British history, had to be sent- then they forfeited the right to govern.
It did happen finally, in 1972, a blood soaked year, the Provisional IRA, a new breed of militant, Marxist influenced nationalists, were ramping things up, the political mistake of internment, the on the ground catastrophe of Bloody Sunday, had fuelled this, Army casualty rates then, were higher than Iraq and Afghanistan now, combined.
The Direct Rule imposition also had for the time, meant the highest deployment of troops at one time, 27,000, as part of the operation to clear away the barricades where the IRA, in particular, ran ghettos.
Using armoured engineering vehicles to do so.
The real fall in troop numbers, came later in the 70's, as much reformed, refreshed RUC began again to do many of the troops taskings, allowing numbers to fall to a 11-12,000 average.
Even in the changed circumstances of later in the 1970's, the view of the role of the Army was unchanged, it was 'Military Aid To The Civil Power', that is, to help to hold the line against an increasingly sophisticated IRA, in the hope that one day, there would be a political solution.
It would take 25 years for this to start in earnest.
The IRA's all out early campaign failed to force the UK government to throw in the towel, they could never sustain this, so the 'long war' policy, but how long is long?
Gerry Adams clearly was convinced, by the end of the 1980's, that this was not working either, since they were nowhere nearer to achieving their goal than before, in fact given the largely sectarian nature of their 'war' by then, they were going backwards.
Adams and others managed to sell the idea, to the rest of the IRA leadership, of his 1992 communication to the UK government, 'the war is over, but we need your help to bring it about', without him ending up tortured, bound, shot and left in a ditch.
The rest is history.
It is worth noting, that many of those over 700 military deaths, were of part time soldiers, murdered off duty, at work, or at home.
That despite this, including similar to the RUC, both security organisations still had no trouble recruiting, (though extreme IRA retaliation/intimidation, made the number of Catholics in uniform fall sharply).
If anything, this alone was a sign that the IRA were not going to succeed.
In the end, they came to the same conclusion the Army had always had, that there was no military solution.