Although it was widely disapproved by Irish opinion at the time, the Easter Rising of 1916 was to prove the foundation event of the modern Irish republic. Crushed in less than a week at the height of the first world war, the uprising and its suppression nevertheless converted much of the population of nationalist Ireland to the cause of independence rather than devolved home rule. The proclamation of the republic outside the GPO building on Easter Monday 1916, together with the men who signed the proclamation and the buildings in Dublin where around 1,500 insurgents fought for it in the following days, have all become enduring Irish public icons.

Argument about the rising has gone on for 100 years and is certainly not over yet, as this year’s richly interesting Irish publishing and media bonanza underlines. The notoriously suffocating tone of the 50th anniversary in 1966, when veterans of 1916 were still alive and the all-Ireland republic was treated as unfinished business, has been replaced by a more open and inclusive approach today, as the rising recedes into history, though without diminishing its narrative potency. The centenary, which is being intensively marked in Ireland and among the diaspora, reaches a formal climax in the delicately choreographed state-sponsored events in Dublin on Sunday which are being snubbed by Sinn Féin and Northern Ireland unionists alike, who both prefer fighting old battles.

However, the rising must also be seen as a watershed event in the history of Britain as well as Ireland. Irish independence in 1922 was the first body blow in the 20th-century break-up of the British empire, even if Ireland was always something of a special imperial case. Meanwhile, a century on, the rising can also now be seen as a precursor of the modern fracturing of the United Kingdom’s internal cohesion. Yet in Britain, with some honourable exceptions, commemoration of the rising has been fitful at best. The lazy habits of closed minds are to blame here. Too few British people know anything of Ireland’s history, including about the rising, which is likely this year to be eclipsed by the centenary of the Somme, where, as it happens, many Irish soldiers died. No one who cares about the study of British history should feel content with this.

Few in either Britain or Ireland saw the rising coming at the time. Fewer still understood where it might lead. The Manchester Guardian of the day shared that failure. “In the nature of a riot rather than a rising,” is how this leader column dismissed Easter 1916, dubbing it “a show – for it cannot be regarded as more than this – of rebellion”. Perhaps that was understandable in the light of the massiveness of the European war. Many more Irish people died on the western front in the week of the Easter rising than died in Dublin, where most of the casualties were in fact civilians caught in crossfire.

Yet even in 1916 the Guardian clearly saw what too many others did not: that overreaction by the authorities, even against the backcloth of war, would play into rebel hands. Summary justice by military courts under martial law sent many to prison and a now famous few to face the firing squad. “The thing is not only wrong, it is pre-eminently foolish,” said this paper. It was right. The result of the executions of the leaders of the rising was what would today be called radicalisation. That lesson is still being very painfully learned even now.

In 2016, the nations of these islands are democratic neighbours with shared traditions, not rulers and ruled. Irish independence is a matter of historical fact, not an open issue. In that sense the question about 1916 for today is not the ahistorical one of whether the 1916 rising was desirable or not. The question is how modern Ireland and modern Britain, and its component nations, can live productively together. That’s proving far easier today than it was 50, never mind 100, years ago. Northern Ireland, in particular, is the better for that – the 1998 Good Friday agreement is one Irish Easter success story without ambiguities. Today’s Ireland suffered to win its independence but is also deeply committed to the strength in numbers of the European Union. If the British want to learn a modern lesson of 1916, it is perhaps that independence and shared sovereignty are not a zero sum game.