As I understand it, the Good Friday Agreement made it significantly easier for travel between NI and Ireland, which was a lot of what the PIRA wanted. Was there ever a shadow of a possibility that they could actually get Britain to surrender NI? Or would it have just been winding down bloodshed over a long period?
Tbh, it was pretty easy to travel between NI and the Rep of Ireland during the troubles. There were security checks but most would go through with no checks and almost no one was turned away. And there was frictionless travel before the troubles started, ie the security was a direct response to the violence. In retrospect, the IRA merely entrenched the unionist position, and apart from release of political prisoners and the dismantling of border military installations (which both only occured because of the IRA campaign) the IRA saw little actual benefit from the troubles and the GFA offered them a convenient way out of the violence.
Another comment in travel between NI and the ROI. Under the Common Travel Area (1923) there was frictionless ttavel between the ROI andtje rest of the UK and NI l, similar to the Schengen area in the EU. Also, under the EU freedom of movement rules brought in when both ROI and UK joined the EU in 1975, citizens of the ROI and UK had the right to travel across the border unhindered.
As i said above, the only checks at the border during the troubles were security checks, they were designed to check for weapons, wanted fugitives etc. They were not stopping anyone getting in or out of NI or the ROI.