Tomorrow is the 30th anniversary of Harold Wilson's deployment of British troops to deal with widespread disturbances in Belfast and Londonderry.
Designed as a short operation to restore peace and order, the military presence has instead become a permanent feature of Irish life.
During the past three decades more than 200,000 soldiers have done tours of duty in Northern Ireland; 500 have been killed.
While some soldiers have been recruited locally, the vast majority are from Britain. The Ministry of Defence said that 152,000 of the soldiers have been stationed there for six months or more; many were there for shorter tours of duty. The total number of officers whoserved, or are still serving, is given as 25,000.
Even though the level of violence has fallen sharply, as hopes for a lasting peace grow, the authorities have thought it prudent not to embark yet on any large-scale reduction in troop levels.
The army is, however, much less visible, having all but stopped its routine patrols. Several hundred extra troops were flown in for the summer marching season, with engineers and other soldiers establishing temporary fortifications at potential flashpoints such as Drumcree, although, in the event, these were not put to the test.
Around 500 regular soldiers have been killed, most of them victims of the IRA. In the same period, troops killed about 300 people, some of whom were IRA members. Many civilians have also been killed, giving rise to a series of political controversies.
The longest-running of these concerned the deaths of 14 people on Bloody Sunday in Londonderry, 1972. A judicial inquiry into the events of that day is presently under way in Northern Ireland.