It was 20 years ago this month when Sinn Féin leader Gerry Adams won the right to visit America after President Bill Clinton gave him a 48-hour visa.

On January 31, 1994, Adams stepped off the plane in New York from Dublin, and Northern Ireland was never the same again.

The international isolation of Sinn Féin was ended forever, and that reality played a huge part in the August 1994 IRA ceasefire, the linchpin of the Northern Ireland peace process.

Looking back now, it seems more extraordinary than ever that Clinton decided to approve the visa despite the opposition of his own State Department, FBI, CIA and speaker of the House, the most Anglophile Irish American I have ever met, Tom Foley

I was deeply involved in the push to get Adams the visa and had spent many hours on the phone with supporters, most notably the late Senator Edward Kennedy, whose influence was so great he counterbalanced all the U.S. agencies and the British government who were apoplectic at the idea.

At a critical moment in the negotiations the British dirty tricks department got involved, having someone call a San Diego British store and threaten to blow it up if the Adams visa did not go ahead.

Laughable as that scenario may seem to be, the White House considered it serious enough that I ended up phoning Adams and asking that he draft a denial that such a crazy scheme had been authorized by him.

I reached him in the middle of the night Belfast time and he was far from pleased.

But he always had a saving sense of humor, asking me if this meant he would have to apologize every time an Irishman took a swing at a British person in a bar.

I will always believe that a New York Times editorial backing the visa on First Amendment grounds played a key factor in the issuance too.

Clinton understandably was looking for the maximum cover if he granted the visa given that he was taking apart the 200-year plus special relationship between the British and U.S. governments.

What was spooky for me was seeing how the British operated when they were in crisis mode. Conversations I had with White House Deputy National Security Advisor Nancy Soderberg were clearly being tapped, and the conversation from her side ran verbatim in a London Sunday newspaper the following week. Edward Snowden would doubtless not have been surprised, but I was.

With such opposition it is not hard to recall just what a magnificent triumph it was for Irish America when Adams finally arrived.

I will never forget being at the Sheraton Hotel when he gave his first public speech and thousands were present. I saw in the faces of all those ordinary Irish people the same hope that must have been there in previous generations when Eamon de Valera visited during the War of Independence, or before that in Fenian times or with Parnell.

It was their night, a night I also remember for staying up late with Adams in his suite trying to polish the speech he was making at the conference organized by businessman Bill Flynn the next day.

Twenty years on and Northern Ireland has come a very long way, but I will always remember the moment when Clinton broke the international isolation and helped make peace possible. We should never forget him or Adams for that.