In his brilliant book, The Telling Year: Belfast 1972, journalist Malachi O'Doherty describes the kind of experience that is too insignificant to make the history books but that nevertheless helps to make history.
One night, a little drunk, he heard soldiers in his back garden and blew a whistle. The next loud sound was the soldiers kicking in the back door of the house. He was dragged out into the garden by a solider who announced "I'm going to shoot you, Paddy", stood him against the wall and pointed his rifle at him.
In fact the soldiers merely beat and kicked him, perhaps because he managed to half-convince them that he really was a journalist. Others in his situation probably did not get off so lightly.
In O'Doherty's little vignette, it is perfectly understandable both that a young man like him might do something stupid and that the soldiers should react violently. In fact, the only thing that is a little surprising is that, in the context of 1972, the victim in this case did not go on to become a terrorist.
This is what happens when you have an army on the streets and it is why armies, of their very nature, tend to create more political problems than they solve. Yet with the longest campaign ever waged by the British army coming to an end at midnight last night, it is not at all obvious that the lessons of this engagement have been learned. If they had been, the British would never have gone into Iraq.
In 1972, the British army had 28,000 soldiers in Northern Ireland - nearly four times more than in the much vaster area of Iraq. Operation Motorman in that year was the largest infantry deployment since the second World War. In all, over a quarter of a million British soldiers have served in Northern Ireland. Those troops were operating in a part of their own country, with all the advantages of linguistic and cultural familiarity, and yet they never achieved their primary goal of defeating terrorism.
Last year, in the foreword to the army's own comprehensive assessment of the campaign, the then commander Gen Sir Mike Jackson, wrote that the campaign was "one of the very few ever brought to a successful conclusion by the armed forces of a developed nation against an irregular force". Yet the report itself is rather more circumspect, concluding, realistically: "Security forces do not 'win' insurgency campaigns militarily; at best they can contain or suppress the level of violence and . . . reduce a situation to an 'acceptable level of violence'."
It can certainly be argued that the British army did achieve this kind of limited success in the 1980s and 1990s. It bolstered a kind of limited stability in which the conflict descended into a constant background obscenity that would flare up from time to time into spectacular atrocity.
Even this ambivalent success, however, can be claimed only by discounting the army's role in raising the conflict to the high levels of the early 1970s in the first place. After its very early role as an emergency fire brigade, the army did more to feed the flames than to quench them.
The army's official assessment is in fact surprisingly honest about this. It points out that the initial phase of an army's involvement in a civil conflict creates a pattern that is hard to change thereafter: "The term 'honeymoon period' is a misnomer. It is not a honeymoon. It is the most important phase of the campaign."
It acknowledges also: "It could be argued that the army did make the situation worse by, in practice, alienating the Catholic community in 1970 and 1971 . . . a desire to 'sort the Micks out' was often apparent."
Both militarily and ideologically, the army was a player, not a referee. As with the paramilitaries, most of the people it killed were civilians: of the 301 people who died at the hands of the British army, 121 were republican paramilitaries and 10 were loyalist paramilitaries. Just as deadly in its own way, though, was the extent to which the army's presence and actions actually supported the IRA's definition of the conflict.
It arrived with a colonial mentality, viewing Northern Ireland as another field for the operations it had run in Malaya, Kenya, Aden and Cyprus and identifying Catholics as the suspect population. (The army's assessment actually confirms what sounded like an apocryphal story that banners used in both Derry and Belfast to order rioters to disperse were written in Arabic.) This turned a complex, largely internecine conflict into an "anti- imperialist struggle" and it took the IRA 30 years to realise that it was fighting the wrong war.
The great irony of Operation Banner is that the army probably learned more from it than its political masters did. Its essential conclusion is that there are no military solutions to political problems and that courageous and intelligent political interventions could have prevented much of the violence.
Soldiers may be a blunt instrument but they learn from experience how relatively impotent they are. It is only messianic politicians who imagine that soldiers can solve long-term problems.