In a 1964 newspaper article, Hume wrote that the Nationalist Party had not produced “one constructive contribution” to the debate in relation to the development of Northern Ireland “in 40 years of opposition”.

He sought to promote change in relation to the chronic housing situation and the lack of a university in his native Derry.

This prompted him to become one of the main architects of the Civil Rights Movement in Northern Ireland. He entered politics in 1969 by standing in the general election, in which he topped the poll in Derry.

Terence O’Neill, the then prime minister of Northern Ireland, had warned that they were “at a crossroads,” and Hume foresaw the real danger of forthcoming violence.

“Surely any intelligent person judging this situation would see that, when one systematically removes all means whereby people can air their grievances democratically, one thereby creates an explosive situation,” Hume warned.

“Militancy can only be strengthened by such intransigence.”

Hume led a march on Magilligan Strand on January 23, 1972, to protest internment. The British Army blocked the march and fired rubber bullets into a crowd that included women and children.

Realising that something terrible could have happened, Hume opposed the march on the streets of Derry the following Sunday, and his worst fears were realised with what would be remembered as Bloody Sunday.

It was the definitive moment when the real troubles started in the North. It focused international attention on Northern Ireland, as no other incident.

Like many Irish politicians before him — Parnell, Pearse, and de Valera — Hume looked to America to change the attitude of the British. But, unlike them, Hume turned to the power elite in Washington, instead of the mass of Irish-Americans.

Traditionally the organised Irish-American community had supported the radical nationalists in Ireland. For instance, Senator Ted Kennedy had initially endorsed calls for support for the Provisional IRA, but Hume had a different approach.

“If we were going to have any success with a political process,” he convinced Kennedy, “we had to stop the flow of arms and funds for arms to the IRA from the US.”

Hume recognised that Congressional resolutions were not the way to effect real change. He worked quietly in the background, enlisting the support of House Speaker Thomas ‘Tip’ O’Neill, along with senators Kennedy and Daniel Patrick Moynihan, and New York governor Hugh Carey. The four of those became known as the Four Horsemen.

As speaker of the House of Representatives, O’Neill was by far the most important, because of his influence with the White House. He was instrumental in enlisting the effective support of three different presidents.

From the outset, Hume was not looking for nationalist supremacy, but for power-sharing between the nationalist and unionist communities.

When the British and Irish governments concluded a power-sharing agreement at the Sunningdale Conference in 1973, Hume enthusiastically endorsed it.

But the agreement was undermined by the implacable hostility of the Loyalist opposition and a distinct lack of real commitment on the part of a weak British government.

The failure to implement power-sharing drove Hume to redouble his efforts to enlist American help. He was criticised within his own party for spending too much time in the US.

His goal was to generate political support for a peaceful Irish settlement and to convince the Americans not to be blinded by their “Special Relationship” with Britain into unquestioning support of British policy in regard to Northern Ireland.

O’Neill got the Four Horsemen to issue a statement on St. Patrick’s Day in 1977, calling for the renunciation of violence.

He then managed to influence then US president Jimmy Carter to draft a statement calling on Americans to become directly involved in a peace initiative.

Carter even promised, if the peace initiative were implemented, the US would provide financial assistance for job creation in the North.

It was novel approach than many considered American interference in British domestic affairs.“I did not really feel that way,” Carter later explained, “I thought it was a challenge to human rights.”

Vocal Irish-American groups, such as the Ad Hoc Committee on Irish Affairs, led by Mario Biaggi, the Irish National Caucus, and Noraid, were all pushing for American support for the Provisional IRA. When Charles Haughey became Taoiseach in 1979, he sought to bolster those groups by recalling Seán Donlon, as the Irish Ambassador to the United States.

Tip O’Neill and Kennedy warned Haughey that he would lose them and the White House. Haughey was forced to back down.

He left Donlon in place, and on his first St. Patrick’s Day as President, Ronald Reagan took the unprecedented step of having dinner at Donlon’s residence.

Despite his enormous influence in the US, Hume did not have much in London, as became apparent when he tried to persuade Margaret Thatcher to avoid a confrontation over the hunger strikes in 1981. Those provided an enormous boost for the IRA.

Hume sought to undo the damage with the New Ireland Forum in 1983. He became the catalyst for more effective co-ordination with Washington in the wake of Thatcher’s contemptuous dismissal of the forum Report.

He got O’Neill to have president Ronald Reagan talk to Thatcher “about the need for progress in resolving the complex situation in Northern Ireland.”

The New Ireland Forum was vital step leading to the Anglo-Irish Agreement of 1985. No Northern Ireland politician, or party, was involved in negotiating that agreement, but the Irish government did confidentially consult with Hume.

Sinn Féin promptly rejected the Anglo-Irish Agreement, and then taoiseach Charlie Haughey even sent Brian Lenihan to US to enlist America hostility, but this proved incredibly inept.

Haughey and Sinn Féin seemed to be on the same side as Ian Paisley who enlisted the public support of 100,000 people in Belfast.

It was like a repetition of the Sunningdale fiasco, but with the help of President Reagan and the Four Horsemen, the Iron Lady was persuaded to stand up to the loyalists this time.

Jeffrey Donaldson concluded that “the Anglo-Irish Agreement was the catalyst within Unionism for a realisation that in the end, we were going to have to sit down and negotiate with Nationalists to find a way forward.”

With the placement of Irish official in the Maryfield Secretariat in Belfast, the Unionists realised that they had overplayed their hand and undermined their veto.

Either they got together with the Nationalists and ran Northern Ireland together, or Britain would do so in consultation with Dublin.

Hume went on to play a major role in involving Gerry Adams in the peace process, after they began meeting secretly in January 1988.

Hume’s real contribution, the author contends, was in persuading “people of all political stripes in Ireland to embrace constitutional politics.”

During his 25 twenty-five years in the European Parliament he formed a working relationship with Ian Paisley by means of providing employment for both communities as a way of uniting disparate elements for their mutual benefit.

The Good Friday Agreement of 1998 was essentially Sunningdale for slow learners, but Hume elevated it above politics by ensuring its ratification in simultaneous referenda on both sides of the border.

Maurice Fitzpatrick highlights the importance of Hume’s contributions in contrast with the brash behaviour of Irish politicians, from Éamon de Valera in the United States during 1919 and 1920, through Charles Haughey’s reckless opposition to the Anglo-Irish Agreement of 1985.

The effectiveness of Hume’s quiet diplomacy stands out all the more in the midst of the current noisy Brexit debate.

John Hume in America: From Derry to DC, by Maurice Fitzpatrick, Irish Academic Press, €24.99.