The military authorities in the Republic warned the Lynch government 31 years ago about a serious and imminent threat to the institutions of the State from republicans and their supporters.
The warning was contained in a secret briefing document on the security situation from the chief-of-staff, Maj Gen Thomas L. O'Carroll, dated August 23rd, two weeks after internment began.
Under the heading, "Interference with the democratic institutions of the State by subversive elements," he wrote: "This is seen as an urgent problem which the Defence Forces may have to meet in the near future."
Maj Gen O'Carroll said: "In the South, active republicans are now believed to number about 1,900, with about 20 to 40,000 active supporters." He had recently been appointed chief-of-staff in succession to Maj Gen P.J. Delaney who had died on July 27th. In a memo written two weeks before he died, and also marked secret, Delaney had outlined a possible armed takeover of the State by republicans and left-wing elements, using street agitation as a cover.
"It is the stated and published aim of subversive organisations to overthrow the existing institutions of the State by force of arms," he wrote. "The methods likely to be employed would probably follow the pattern of events in NI. Controversial social and political issues would be exploited in order to create a situation of civil disorder. This is most likely to occur in Dublin, but the possibility of simultaneous action in other places such as Cork, Limerick, Galway and Waterford can NOT be excluded.
"The minimum requirements in personnel to meet a situation of civil disorder in Dublin, in which the Defence Forces would be called out in aid of the Civil Power, would be a force of two infantry battalions, three cavalry squadrons and one military police company. These units should be based in Dublin or within reinforcement distance of it."
The Delaney memo is dated July 13th, three weeks before internment. It was a rapidly changing situation and at that stage the main danger appeared to stem from the "probability" of precipitate change in Britain's military policy on the North.
The memo stated: "There is a distinct probability that at some future date, perhaps sooner than might seem possible at present, British forces would be withdrawn from Northern Ireland, either to meet a crisis elsewhere, or by decision of the British parliament. The vacuum thus created would create a situation of grave peril for the country as a whole." Eight days earlier, on July 5th, Maj Gen Delaney wrote to the Minister for Defence, Mr Jerry Cronin, about "the general unpreparedness of the Defence Forces to undertake the scale of operations, which the government might find necessary in order to preserve the security of the State".
Maj Gen Delaney said constraints on expenditure over the years meant that the Defence Forces had been allowed to run down: "In the light of the present situation I am deeply concerned at the low standard of effectivity of the Forces."
The newly-released documents reflect the fact that the civil disorder which followed the introduction of internment aroused government concerns in Dublin about a threat to the Republic and the consequent need to take appropriate measures.
In a memo to the Minister dated August 13th, Maj Gen O'Carroll referred to "your direction to me on 10 Aug '71 to prepare the Defence Forces for an internal security situation".
This would mean calling up the First Line Reserve and an unprecedented call-up of "selected members" of the FCA.
The chief-of-staff's subsequent memo of August 23rd appears to arise out of a meeting he had with the minister and his cabinet colleague, George Colley. "The object of this paper," O'Carroll wrote, "is to set out the various contingencies in relation to the security of the State and the situation in Northern Ireland as outlined to the chief-of-staff by the Minister for Defence and the Minister for Finance (Colley) on 17th August, 1971, and to examine the military considerations arising therefrom".
The contingencies as outlined by the chief-of-staff were as follows: "A - The interference with the democratic institutions of this State by subversive elements. B - Incursions into the Republic by organised Security Forces or partisan (i.e. loyalist) elements from N. Ireland. C - A situation developing in N. Ireland which might justify incursions into that area by elements of our Forces. D - A situation developing in N. Ireland following a withdrawal of the British Armed Forces from that area which might justify incursions by elements of our Forces."
On Contingency A, the chief-of-staff noted the difficulties the British army was having in the North, despite its greater numbers. Calling-up the First Line Reserve and selected FCA members to help deal with a subversive revolt in the Republic was only "an emergency measure to meet a possible rapid deterioration of the situation".
FCA members were not an adequate substitute for trained regular personnel.
On Contingency B, he outlined the circumstances where security forces or loyalist groups from the North might cross the Border. Dealing with these possibilities would require an increase in military strength and more Border patrols.
Whereas previously-released Army documents dwelt at length and in some detail on the implications of a possible cross-Border incursion in the event of a "doomsday situation" in the North, O'Carroll considered Contingency C more briefly:
"a. This action would be an act of war and would almost certainly provoke countermeasures on the part of the British Forces."
"b. The most likely counter-measures could include - (1) invasion, to destroy our offensive potential; (2) invasion, to occupy part or all of our territory for a limited time; (3) aerial or naval bombardment of selected ports, airfields, industrial or prestige targets.
"c. In view of the present disparity which exists between the Forces (both organised and partisan) in Northern Ireland and the Defence Forces in strength, equipment, air, armour, reinforcement and resupply, such action could NOT be considered as anything more than a gesture.
"No penetration in depth could be made and in the face of the superior forces which could be mustered against the invasion, destruction, capture or withdrawal of the Force would be inevitable."
"d. It is the military view that if such a course is seriously contemplated, it would call for the full mobilisation of the nation's resources in manpower and call for the procurement and stock-piling of all forms of warlike stores and other equipment. To provide a platform for such mobilisation a Permanent Defence Force at full strength would be an essential prerequisite.
"e. It must also be stated that even the full mobilisation of the national resources could not ensure a successful outcome in view of Britain's air, naval and industrial potential."