LONDONDERRY, Northern Ireland (Reuters) - Thousands lined the streets of Martin McGuinness’ home town on Thursday for the funeral of the Irish Republican Army commander who became a cornerstone of Northern Ireland’s peace.

The coffin of Martin McGuinness is carried through crowded streets during his funeral in Londonderry, Northern Ireland, March 23, 2017. REUTERS/Clodagh Kilcoyne

Former U.S. President Bill Clinton was among the key figures from the peace process who traveled to pay their respects to the nationalist Sinn Fein politician, who died on Tuesday at the age of 66 from a rare heart condition.

McGuinness remains a figure of hate for many pro-British Protestants in Northern Ireland for his senior role in the IRA, which killed over 1,600 people in three decades of violence aimed at breaking Northern Ireland from the United Kingdom and uniting it with the Irish Republic.

But he is a hero to others for defending his community from what was seen as a hostile British state, and for his role as one of the lead negotiators in the 1998 peace deal that largely ended the violence.

“After all the breath he expended cursing the British, he worked with two prime ministers and shook hands with the Queen,” Clinton, whose hands-on role was central to brokering peace, told the 1,500 people packed into Saint Columba’s Church while others listened outside or watched on a big screen nearby.

“He persevered and he prevailed, he risked the wrath of his comrades and rejection of his adversaries. If you really came here to celebrate his life and honor the contribution of the last chapter of it, you have to finish his work.”

McGuinness’ coffin, draped in the Irish tricolor flag, earlier left his house in the Catholic Bogside neighborhood of Londonderry, near the spot where British soldiers opened fire at a crowd of Catholic protesters on “Bloody Sunday” in 1972, killing 13.

It was carried part of the way by Sinn Fein members including Gerry Adams, past murals commemorating the Bloody Sunday victims and jailed IRA members who died on hunger strike a decade later - major turning points in the sectarian conflict.

Led by pipers playing traditional Irish music and followed by a sea of mourners, many dressed in black with white lily pins, the procession passed houses flying the tricolor from their windows. Some shouted “our hero” as the coffin passed.

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“A COMPLEX MAN”

McGuinness was instrumental in convincing a reluctant IRA to lay down its weapons and agree to a peace deal that created a power-sharing government and gave the Republic of Ireland a say in Northern Ireland affairs.

Priest Michael Canny said McGuinness knew only too well how many people struggled with his IRA past, but that the presence of so many people in the church whose attendance would have been unthinkable only a short generation ago was an eloquent testimony to “a complex man”.

Clergy from other religious denominations also spoke during the service.

“He changed the fabric of Northern Ireland for good. People are in a better place because of him,” said Nancy O’Neill, in her 70s, who traveled with her family from the neighboring county of Tyrone.

Antoinette McGuinness, 66, traveled from Leitrim in the Irish Republic and said she was among bus loads of mourners who made the trip across the border.

“I’m here to see history,” she said. “The Catholics here had nothing. They were downtrodden for too long. He brought it right round from beginning to end. It’s a shame he won’t be here to see the result.”

His last act in politics was to withdraw his party from the government in January, citing the “deep-seated arrogance” of unionist leader Arlene Foster. Foster, whose father narrowly escaped alive from an IRA shooting, spoke warmly of McGuinness in parliament on Wednesday and was applauded as she arrived at the service.

Ireland’s president and prime minister also attended, alongside Britain’s Northern Ireland minister. The flag at the Irish parliament was flown at half mast.

Former U.S. President Barack Obama said in a message of condolence that McGuinness “had the wisdom and courage to pursue peace and reconciliation” and that his leadership was instrumental in turning the page on the past.

In a graveside oration to his friend of over 40 years, Sinn Fein President Adams said Ireland had lost a hero.

“Martin made an unparalleled, astonishing journey. Thanks to Martin we now live in a very different Ireland, which has been changed utterly,” he said.