US president Barack Obama has left Ireland for London ahead of schedule to avoid any travel problems that could arise from an ash cloud casued by an Icelandic volcano.
Mr Obama, First Lady Michelle and members of his entourage left Dublin airport on Air Force One at 9.28pm, just 12 hours after landing in Ireland. They were initially scheduled to stay in Ireland until tomorrow morning.
During the visit, Mr Obama said Ireland and the US were bound by “history, affection and bonds of friendship".
Addressing a crowd of up to 60,000 people at College Green in Dublin this evening, Mr Obama said never has a nation so small inspired so much in another. "Irish signatures are on our founding documents. Irish blood was spilled on our battlefields. Irish sweat built our great cities"
"When we strove to blot out the stain of slavery and advance the rights of man, we found common cause with your struggles against oppression. Frederick Douglass, an escaped slave and our great abolitionist, forged an unlikely friendship right here in Dublin with your great liberator, Daniel O'Connell," he said.
To rousing cheers he introduced himself as: “Barack Obama, of the Moneygall O’Bamas. I am here to find the apostrophe that we lost along the way”.
He thanked the crowd for extending him a warm welcome: "Thank you to the citizens of Dublin and Ireland for the warm and generous hospitality you have shown me and Michelle. It certainly feels like 100,000 welcomes. We feel very much at home. I feel even more at home after that pint I had. I feel even warmer.
"In return, let me offer the hearty greetings of tens of millions of Americans who proudly trace their heritage to this small island. They say hello."
Mr Obama also paid tribute to former taoiseach Dr Garret Fitzgerald, who died last week and discussed the economic crisis. He said Ireland had faced trials before which it had endured and overcome. "We're people, the Irish and the Americans, who never stop imagining a brighter future."
Today's speech was the final official engagement of his visit to Ireland and the president is to cut short his visit and depart from Dublin airport this evening. The early departure is based on fears that an ash cloud from the erupting volcano in Iceland may force the closure of Irish air space tomorrow and effectively trap him here.
The crowds gathered early this afternoon to hear the president's speech with the queue going past Lord Edward Street and sneaking up past Burdocks on Werburgh Street. Those who were lucky enough to gain access to College Green were entertained by artists including Westlife, Jedward and Imelda May.
GAA commentator Micheál Ó Muircheartaigh introduced a number of prominent Irish sports stars to the crowd including the Irish rugby team captain Brian O'Driscoll, boxer Katie Taylor, Republic of Ireland captain Robbie Keane and golfer Padraig Harrington. In addition, a number of leading actors including Stephen Rea, Saoirse Ronan and Daniel Day-Lewis appeared on stage and addressed the cheering crowds.
Mr Obama was introduced onstage by Taoiseach Enda Kenny who told the cheering crowds that the 44th American president "had come home". "Last week Queen Elizabeth came to our shores and bowed to our dead. The Irish harp glittered above the heart of the English Queen. With pride and happiness and two words of Irish we closed a circle of our history," said Mr Kenny.
"Today, with president Obama we draw another circle, one in which we tell the world of our unique, untouchable wealth. Wealth that cannot be accumulated in banks or measured by the markets or traded on the stock exchange because it remains intact and alive, deep inside our people, in the heart-stopping beauty of our country and in the transforming currency of the Irish heart, imagination and soul," he added.
During his speech Mr Obama focused on the many connections between Ireland and the US.
"Now, of course, an American doesn't really require Irish blood to understand that ours is a proud, enduring, centuries-old relationship; that we are bound by history and friendship and shared values. And that's why I've come here today, as an American president, to reaffirm those bonds of affection," he said.
Commenting on the country's economic crisis the president said that "as trying as these times are, I know our future is still as big and as bright as our children expect it to be."
"You're a people who modernised and can now stand up for those who can't yet stand up for themselves. And this is a nation that met its responsibilities - and inspired the entire world - by choosing to see past the scars of violence and mistrust to forge a lasting peace on this island," he said.
"We're people, the Irish and Americans, who never stop imagining a brighter future, even in bitter times. We're people who make that future happen through hard work, and through sacrifice, through investing in those things that matter most, like family and community," he added.
Ending his speech, the president returned to the catchphrase which he used during his election campaign.
"Ireland, if anyone ever says otherwise, if anybody ever tells you that your problems are too big, or your challenges are too great, that we can't do something, that we shouldn't even try - think about all that we've done together. Remember that whatever hardships the winter may bring, springtime is always just around the corner. And if they keep on arguing with you, just respond with a simple creed: Is féidir linn. Yes, we can. Yes, we can. Is féidir linn."
Following his speech, Mr Obama went down into the crowds and shook hands with members of the public and had his picture taken with some of them before departing in his motorcade.
He is understood to have had dinner with US ambassador Dan Rooney before travelling to Dublin airport to depart for his state visit to England.
Traffic restrictions in Dublin have now been lifted.
