In a shock speech, British Prime Minister David Cameron has announced his resignation.
"I think the country requires fresh leadership," he said.
This comes after the success of 'Leave' in the Brexit vote, in spite of Mr Cameron campaigning to stay, and facing off with Brexit supporters from within his own Conservative Party.
When he promised the referendum, in 2013, Mr Cameron said it would "settle this European question in British politics" once and for all.
He called the referendum to puncture growing support for the anti-EU UK Independence Party and placate the strongly eurosceptic right wing of the Conservatives.
Mr Cameron said he accepted the decision of the electorate, which voted by 52 percent to 48 percent to quit the EU.
"The British people have made a very clear decision to take a different path, and as such I think the country requires fresh leadership to take it in this direction."
He said there was "no doubt about the result," and he reassured investors that Britain's economy would remain strong, and there would be no immediate changes.
"I will do everything I can as Prime Minister to steady the ship over the coming weeks and months, but I do not think it would be right for me to be the captain that steers our country to its next destination," said a downcast Mr Cameron.
"This is not a decision I've taken lightly, but I do believe it's in the national interest to have a period of stability, and then the new leadership required."
He asked for the full cooperation between England, and the other countries in Britain, and said he would leave it to his successor to invoke Article 50 of the Lisbon Treaty, which begins the two-year process of negotiating a new trade relationship with the UK's former partners.
Other politicians spoke of the need for national unity.
"I believe that Britain is better off within the European Union, but the British people have clearly spoken today, and their democratic will must now be fulfilled," said mayor of London Sadiq Khan.
"We all have a responsibility to now seek to heal the divisions that have emerged throughout this campaign - and to focus on that which unites us, rather than that which divides us."
Mr Cameron said this would require "strong, determined, and committed leadership," and "we should aim to have a new Prime Minister in place by the start of the Conservative Party conference in October."
"I will continue in post as Prime Minister, with my cabinet, for the next three months."
The referendum campaign was unexpectedly bitter and divisive, and was brought to a shocked halt when Labour MP Jo Cox was shot and stabbed to death in the street last week.
Ultimately, many voters proved resistant to Mr Cameron's message that Britain is stronger, safer and more economically secure within the EU than it would be outside it.
This was echoed by US presidential candidate Donald Trump, currently in Britain, who said "It's fantastic, the Brexit vote -- Britain has taken back control of their country."
Mr Cameron's announcement will trigger a battle for the Conservative leadership -- and the keys to No.10 -- which is likely to feature Brexit standard-bearer Boris Johnson taking on figures such as Home Secretary Theresa May.