The IRA Green Book was a training and induction manual issued to all new recruits. It explained the IRA’s purpose, mission and methods, stressing the need for secrecy and commitment. This extract from the 1977 edition explains the different categories of enemy confronted by the IRA:

“The enemy, generally speaking, are all those opposed to our short-term or long-term objectives. But having said that, we must realise that all our enemies are not the same and therefore there is no common cure for their enmity. The conclusion then is that we must categorise and then suggest cures for each category… We have enemies through ignorance, through our own fault or default, but of course the main enemy is the establishment.

The enemy through ignorance we attempt to cure through education, though such an attempt is obviously futile if we do not firstly educate ourselves. Our means are marches, demonstrations, wall slogans, press statements, Republican press and publications, and of course person-to-person communication. But as has already been stated, we must first educate ourselves, we must organise the protests and demonstrations efficiently, we must be prepared to paint the wall slogans and to sell and contribute to Republican press, publications and press statements.

The enemy through our own fault or default is the one we create ourselves through our personal conduct and through our collective conduct of the struggle: the wee woman whose gate or back door gets pulled off its hinges by a volunteer evading arrest and who doesn’t get an apology as soon as possible afterwards, or more preferably has the damage repaired by one of our supporters; the family and neighbours of a criminal or informer who has been punished without their being informed why. In brief, our personal conduct, as well as our conduct of our Republican activities, must be aimed at if not enhancing support, at least not creating enemies unnecessarily.

The establishment is all those who have a vested interest in maintaining the present status quo: politicians, media, judiciary, certain business elements and the British war machine compromising the British Army, UDR [Ulster Defence Regiment], RUC [Royal Ulster Constabulary], Screws [British prison guards], Civilian Searchers. The cure for these armed branches of the establishment is well known and documented. But with the possible exceptions of British ministers in the Northern Ireland Office and certain members of the judiciary, the overtly unarmed branches of the establishment are not so clearly identifiable to the people as our enemies…

It is our task therefore to clearly identify them to the people [as our enemies]… Execution, as earlier stated, is not the only way of making this category of establishment enemy ineffective: we can variously expose them as liars, hypocrites, collaborators, make them subjects of ridicule…”