THe "Peace Lines" in your link are thaose that have become necessary since Britain forcibly partitioned Ireland and created a sectarian state
They were put in place in 1969 when a Civil Rights march demanding equal rights with the two thirds majority which had been created by artificially dividing Ireland into two separate states

In essence, the warring factions were not Irish versus Irish but Irish Catholics fighting Britons
You might like to bear this fact in mind - originally the intention was to make the whole of Ulster a State - them someone did the math and realised that this would not create the majority Britain needed, so the knocked off three of the Ulster Counties - Ireland was deliberately divided into a sectarian dominated State
It was the dominant sectarian Loyalists who fired the first shots in The Troubles, just as it was the same people who threw te stones and turned peaceful protests into a murderous bloody war
The Irish have never been at war with The Irish - Britain has always been regarded as the oppressor
I suggest you read what you put up - the information is all there
Jim