Ireland’s new government will have to navigate all of this at a time when relations with Britain have been strained by the Brexit process — including the delicate question of how to handle the border with Northern Ireland, a territory that remains under British control and, after Brexit, out of the European Union.

“A lot of what has happened in the last three years has brought out militancy in people who thought they were quite moderate nationalists,” said Diarmaid Ferriter, a history professor at University College Dublin. “Three years of listening to the debate about the border, and to British ignorance about Ireland, have allowed a reflex anti-British sentiment to come to the fore.”

Henry Patterson, an emeritus professor of history at the University of Ulster in Northern Ireland, said the dispute over the R.I.C. threatened to feed into destructive sectarian passions.

“If you can’t recognize the humanity of these people, and what was done to them, as well as what they did to other people,” Mr. Patterson said, “we are really into the worst kind of tribal narrative about Irish history.”

The current backlash erupted at a time when many people south of the border had been gaining a more nuanced understanding of the old R.I.C.

Founded as a heavily armed colonial police force, it was expected to protect Anglo-Irish landlords from their impoverished Irish tenants, oversee evictions and quell political unrest. But in quieter times its constables earned acceptance and even respect through ordinary police work. Most of its rank-and-file members were recruited from the same class of Catholic farmers and merchants who provided the bedrock for Ireland’s struggle for independence.