LONDON (Reuters) - Paddy Ashdown, the face of centrist politics in Britain for more than a decade and a one-time marine commando who sought to secure peace in the former Yugoslavia, died on Saturday after being treated for cancer. He was 77.

FILE PHOTO: Paddy Ashdown, former leader of the Liberal Democrats, speaks to delegates at an evening rally at the party's autumn conference in Glasgow, Scotland October 4, 2014. REUTERS/Russell Cheyne/File Photo

Ashdown led the Liberal Democrats for 11 years up to 1999, steering it to become a campaigning force in British politics against the Conservatives and the Labour Party.

The party said Ashdown died on Saturday evening after a short illness. He had recently been hospitalized with bladder cancer.

It said he would be remembered as someone who made an immeasurable contribution to furthering the cause of liberalism.

Tributes came in from across the political spectrum. Prime Minister Theresa May said Ashdown served his country with distinction. “He dedicated his life to public service and he will be sorely missed,” she said in a statement.

Calling Ashdown a “true patriot”, former Conservative Prime Minister John Major said: “In Government, Paddy Ashdown was my opponent. In Life, he was a much valued friend.”

Jeremy John Ashdown was born in India on Feb. 27, 1941, the eldest son of an Indian army colonel. When he was five, his father became a pig-farmer in Northern Ireland.

He was educated at an English private school where he earned the nickname Paddy because of his strong Irish accent.

He spent years in the Royal Marines, and was on active service as a commando in the jungles of Borneo. He entered parliament in 1983 and was virtually unknown when he became leader of the pro-European party five years later.

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However his craggy good looks - he had short sandy hair - and an earnest expression swiftly helped him to become one of his country’s most popular leaders and for a time the “Mr Clean” of British politics.

He also gained in stature during the 1991 Gulf War, which allowed him to display his military experience and diplomatic skills.

Ashdown’s image as a family man above the sniping of mainstream politics took a hit in February 1992 when he was forced to admit to a brief extra-marital affair with his secretary.

Having stood down in 1999, he went on to become the United Nations high representative and European Union special representative for Bosnia and Herzegovina.

Ashdown described himself as having few gifts other than strong willpower.

“People said I couldn’t learn Chinese, they said I couldn’t run 30 miles in six hours. This sounds extraordinarily arrogant but I can’t remember a thing upon which I’ve set my mind that I didn’t succeed in doing,” he said in early 1992.

He was replaced as head of the party by Charles Kennedy who enjoyed further electoral success when he opposed Blair’s decision to invade Iraq, and the party under Nick Clegg entered power in a coalition David Cameron’s Conservatives in 2010.

It has since been decimated at the polls.

Ashdown, the author of several books, had two children with his wife, Jane.

He had in recent years campaigned alongside Cameron and other leaders for Britain to remain within the European Union. He warned that chaos could ensue if it voted to leave and described Brexit as “a sense of personal bereavement”.