US President Donald Trump (L) congratulates Senior Counselor to the President Stephen Bannon during the swearing-in of senior staff in the East Room of the White House on January 22, 2017 in Washington, DC - AFP

A defiant Steve Bannon declared the Trump presidency he had campaigned for was over as he vowed to carry on the fight after being ousted as the White House chief strategist.

Within hours of leaving his office, Mr Bannon was back at Breitbart, the right wing website he ran, presiding over the evening news conference.

In interviews he made it clear he was not going quietly as he rounded on those he held responsible for his departure.

“The Trump presidency that we fought for, and won, is over," he told the Weekly Standard, a right-wing newspaper “We still have a huge movement, and we will make something of this Trump presidency," he continued.

"But that presidency is over. It’ll be something else. And there’ll be all kinds of fights, and there’ll be good days and bad days, but that presidency is over.”

He added: “I feel jacked up. Now I’ve got my hands back on my weapons,” he added as he vowed “Bannon the barbarian” would crush the opposition.

"There’s no doubt. I built a -----ng machine at Breitbart. And now I’m about to go back, knowing what I know, and we’re about to rev that machine up. And rev it up we will do.”

His loyalty to Donald Trump remained undimmed.

“If there’s any confusion out there, let me clear it up: I’m leaving the White House and going to war for Trump against his opponents -- on Capitol Hill, in the media, and in corporate America,” he told Bloomberg.

Earlier Sarah Huckabee Sanders, White House press secretary said Mr Bannon, 63, had departed “by mutual agreement.”

The White House then issued a statement, saying that the decision was agreed by Mr Bannon and John Kelly, the chief of staff – a sign of Mr Kelly’s grappling to control the chaos, or perhaps simply to avoid Mr Trump having to put his name to the firing of the man who most connects him to his diehard supporters.

Joel Pollack, Breitbart's editor at large, tweeted a one-word response to Mr Bannon’s departure: “War”.

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Mr Bannon was controversial from the start.

Combative and unapologetic, the former Goldman Sachs financier was employed by Mr Trump as his campaign manager in August 2016, and described at the time as “the most dangerous political operative in America”.

He urged Mr Trump to pursue a populist path, and pressed him to hammer Hillary Clinton as corrupt - reportedly coming up with the “lock her up” chant that reverberated around his rallies.

It was Mr Bannon, with fellow hardliner Stephen Miller, who wrote Mr Trump’s inauguration speech – a dark and foreboding depiction of the “American carnage” that Mr Trump believed he had been elected to stop.

He was often at odds with the "globalist" wing of the White House - Jared Kushner, Mr Trump's son-in-law; his wife Ivanka Trump; H.R. McMaster, the head of the national security council; and Gary Cohn, director of the national economic council.

Mr Bannon reportedly referred to them in private as “the New Yorkers” and “the Democrats”, among more printable nicknames, and tried to steer his boss away from them and towards his own nationalist sympathisers.

At first the president thought fondly of his flame-throwing ideologue, who was seen to wield immense behind-the-scenes power inside the White House.

Saturday Night Live depicted him as the grim reaper, playing Mr Trump like a puppet - something that reportedly amused Mr Bannon, but enraged his boss.

His departure had been described as imminent before, but since Charlottesville the drum beat of demise rose to a frenzy.

Steve Bannon at Trump Tower in November 2016

Mr Trump was reported earlier this week to have not spoken face-to-face with Mr Bannon in over a week, and on Tuesday, at the now infamous press conference in which he defended white supremacists, Mr Trump could only offer a lukewarm endorsement, responding to a question about Mr Bannon's future with: "We'll see."

That press conference sparked condemnation of a president never before seen in the United States – the heads of the military spoke out against their commander-in-chief, and the UN secretary-general voiced concern. Titans of industry who Mr Trump had so assiduously courted on the campaign trail deserted him in droves, leading to the folding of both his business advisory panels.

On Friday the arts council resigned en masse – the first White House agency to do so.

Political condemnation was also snowballing, leading astonished Americans to ask where this could all end.

Bob Corker, a senior Republican loyalist and chair of the Senate foreign relations committee, who was considered for secretary of state, declared that "the president has not yet been able to demonstrate the stability nor some of the competence that he needs to" in dealing with crises.

And, while Mr Trump sought to shift Thursday from the white supremacists to the future of statues, he was criticised by Rupert Murdoch’s son James, in an email widely circulated.

"I can't believe I have to write this: standing up to Nazis is essential; there are no good Nazis. Or Klansmen, or terrorists," he wrote.

Rumblings of discontent from Mr Trump's staff grew so loud that the White House was forced to release a statement saying that Gary Cohn, Mr Trump's chief economic adviser, was not quitting.

The Dow Jones suffered its worst day since May on Thursday, but rebounded slightly on the news that Mr Cohn, a former president of Goldman Sachs, was staying put.

Mr Cohn will certainly not be crying over the departure of Mr Bannon. Mr Bannon perhaps sealed his own fate this week by telephoning a reporter with The American Prospect, a Left-wing publication, to contradict his boss - and suggest that he was deciding who was in and who was out in the state department.

“There’s no military solution [to North Korea’s nuclear threats], forget it,” said Mr Bannon, directly undermining Mr Trump's vow to respond if attacked.

Asked about his rivals at the departments of state, defence and treasury, who wanted to keep China on side by avoiding trade wars, Mr Bannon was unrepentant.

“They’re wetting themselves,” he said. “I’m changing out people at East Asian Defense; I’m getting hawks in.”

But Mr Bannon may not go quietly.

One of the reasons Mr Trump was said to have delayed dismissing him was fear of “weaponising” Mr Bannon, if he was unleashed from the White House.

A friend of Mr Bannon said he intended to return to Breitbart, adding: “This is now a Democrat White House”.

Arnold Schwarzenegger has some advice for Donald Trump

4:23AM

Bannon 'in good spirits'

Quoting a "friend", the Wall Street Journal, said Mr Bannon seemed to be in good spirits, following his departure from the White House.

“Steve has always been a gunslinger. This allows him to be a gunslinger again.”

3:29AM

Trump 'ceding dangerous ground to the media and establishment'

Kristin Tate, a conservative columnist, warns that Donald Trump has ceded dangerous ground to the establishment.

"There is no compromise with the Never-Trumpers and Democrats over the role of chief strategist," she writes in The Hill, a political website.

" Personnel is policy, and Trump is ceding his ace for a player to be named later. That’s not good enough for the people who made his movement happen.

2:22AM

Bernie: The problem wasn't Bannon, it was Trump

The problem was never just Steve Bannon. It was and always will be Donald Trump. https://t.co/cTBqwdwZUW — Bernie Sanders (@SenSanders) August 18, 2017

2:21AM

Steve Bannon 'said he resigned from White House two weeks ago'

Steve Bannon just told me he resigned from the White House two weeks ago @POTUS#Bannon — Sara A. Carter (@SaraCarterDC) August 18, 2017

1:55AM

CNN says 'Gorka could go'

Citing unnamed "sources", CNN is saying that Sebastian Gorka, Donald Trump's deputy assistant, could be the next to go.

Born in the UK to Hungarian parents, British educated Mr Gorka, has also been a controversial figure in the White House.

Sebastian Gorka Credit: Alex Wong/Getty

Seen as a hardliner, he was openly critical of Rex Tillerson, the secretary of state, when he suggested the US could negotiate with North Korea over nuclear weapons.

But Mr Trump is reported to be a fan of Mr Gorka's combative style and his forthright defence of the administration in his media appearances.

1:15AM

Another White House departure

Steve Bannon is not the only senior figure leaving the White House, according to Politico.

George Sifakis, director of the Office of Public Liaison since March, is reportedly on his way out.

A close friend and ally of Reince Preibus, the former White House chief of staff, Mr Sifakis was an aide to George W Bush.

8:51PM

Nigel Farage says Bannon will be missed

Very sorry to see my friend Steve Bannon go. His political brain will be hard to replace. — Nigel Farage (@Nigel_Farage) August 18, 2017

8:22PM

Bannon meets billionaire donor to plot next steps

Axios, the authoritative Washington website, reports that Mr Bannon met with billionaire Republican donor Bob Mercer to plan their next moves.

They write:

Bob Mercer and Steve Bannon had a five hour meeting Wednesday to plot out next steps, said a source withknowledge of the meeting. They plotted strategy going forward — both political and media strategy. The meeting was at Mercer's estate on Long Island. Mercer had dinner the next night at Bedminster with President Trump and a small group of donors. The source said Mercer and Bannon "remain strong supporters of President Trump's and his agenda."

8:19PM

Democrat leader responds

Steve Bannon's exit does not erase @realDonaldTrump’s long record of lifting up racist viewpoints & advancing repulsive policies. #BannonOut — Nancy Pelosi (@NancyPelosi) August 18, 2017

8:03PM

Four down...

This January 28 photo shows Donald Trump and his advisers inside the Oval Office. Of the six in the picture, only the president and vice president remain - Reince Priebus, Michael Flynn, Sean Spicer and Steve Bannon have all left.

7:48PM

Breitbart's editor-at-large responds to Steve Bannon's ouster