Manchester United and Celtic legend Paddy Crerand, both of whose parents were from Donegal, met with members of the IRA in Derry in 1975 in a bid to get them to speak to John Hume.
The revelation comes in his memoir, 'Never Turn the Other Cheek', which has just been published.
Crerand, who spent much of his childhood in West Donegal and who owned a hotel in Gweedore in the 1970s, came to Derry to try to resolve a split in the nationalist community caused by the rent strikes of 1975.
Crerand said: "I was a big friend of John Hume, who was then a teacher in Derry."
The friendship between the two men led to Crerand's personal intervention in 1975 in the simmering row between the SDLP and the IRA.
They had fallen out over the tactic of trying to hurt the authorities by refusing to pay rent. This had resulted in electricity and water being cut off in some cases, and the movement was torn between moderates who wanted to negotiate a deal and more militant Republicans who wanted to press on.
Crerand said: "In 1975, people weren't going to pay their rates or rent in Derry, so I said to John: 'This can't go on. Ordinary people will suffer and you are never going to solve this unless you speak to people."
"He said: 'They (the Republican movement] won't speak to me.' I said to John: 'I'll see what I could do,' so, with the help of a friend of mine, the late Jim Harkin, I organised a meeting with them in Derry."
Crerand freely admits that they only spoke to him "because I had been a well-known footballer."
He said: "Martin McGuinness was obviosuly the leader of the pack. I just went in to talk to them. They weren't political at all. They were all working class lads and right, left or centre, all they wanted was the Brits out of Ireland. It was not a political movement, and only became political afterwards.
"I said to them: 'Why won't you speak to John Hume?' I pointed out to them the people who were against the Republicans were all together, 'but you lot are all fighting with each other. What chance have you got? If you all get together and become one, it gives you a bigger voice', but they didn't want to know.
"We spoke mostly about football, but they were adamant they were going to do their own thing. I told them they were all f***ing mad. You get six Irishmen in a pub anywhere and they'll all fall out with each other, and they were all just like that.
"I told them they needed to become political and renounce violence if they wanted to achieve their aims, and that the only way of solving their problems was by dialogue, and by not shooting each other."
He added: "I didn't think of it as a courageous thing. It was 2am and the army was everywhere and the relative who had come with me was petrified, especially when we had to drive back across the border at that time in the morning, which was not a healthy thing to do.
"I went back and told John what had happened and nothing came of it. I never met Martin McGuinness again until George Best's funeral."
Crerand is "amazed and delighted" that peace has come to Northern Ireland. He said: "I never thought I'd see Martin McGuinness sit down with Ian Paisley, and I thank God for it."
Paddy Crerand played 396 times for Manchester United and won the European Cup in 1968.