Next Friday will be the 10th anniversary of the largest demonstration in British history.
On that momentous day millions of people around the country took to the streets to oppose the looming war in Iraq.
The Chartist public meetings in the 1840s, the Suffragette marches to Hyde Park in the early 20th century, CND's huge protests in the 1980s - in terms of numbers February 15 2003 dwarfed them all.
However, a common refrain today is that the march was, as one UK Uncut activist put it, "an absolute failure."
Or as the broadcaster Michael Goldfarb said in a BBC radio documentary about protesting, "It changed absolutely nothing."
When he spoke to me for my new book The March That Shook Blair, peace activist Milan Rai strongly disagreed with this popular argument.
"If someone was to say the anti-war movement achieved nothing, I think that is plain, flat wrong," he explained.
"We achieved a lot, and a hell of a lot more than we realise."
As everyone knows, the Blair government invaded Iraq in the face of overwhelming public opposition and contrary to international law.
What is far less well known is the fact the anti-war movement came very close to derailing Blair's push to war. We were not ignored.
At the time Blair's rhetoric was all about strong leadership and standing firm against Saddam Hussein.
In contrast, a careful reading of news reports and recently published insider accounts shows a prime minister under intense political pressure, a government in continual crisis and, most importantly, a government close to falling.
The Spanish ambassador to the United Nations noted that the British government was "nervous" and "exclusively obsessed" with domestic public opinion.
"The anti-war mood was definitely growing," Alastair Campbell wrote in his diary on January 22 2003.
On March 9 development secretary Clare Short had threatened to resign and there was a real concern within Blair's inner circle that the government might not win the parliamentary vote on the war.
Those working in No 10 were "examining what was in their drawers to see how easily it was portable because he [Blair] was on a knife edge," remembers Jeremy Greenstock, the British ambassador to the UN at the time.
Receiving worrying reports from its embassy in London, Washington was so concerned about Blair's position that on March 9 president George W Bush told his national security adviser Condoleezza Rice: "We can't have the British government fall because of this decision over war."
Bush then called Blair and suggested that Britain could drop out of the initial invasion and find some other way to participate.
Bush made his offer three times and Blair refused three times.
Two days later was what has become known as "wobbly Tuesday" - "the lowest point of the crisis for Mr Blair," according to the Sunday Telegraph.
The same report explained that the Ministry of Defence "was frantically preparing contingency plans to 'disconnect' British troops entirely from the military invasion of Iraq, demoting their role to subsequent phases of the campaign and peacekeeping."
The Sunday Mirror reported that defence secretary Geoff Hoon had phoned his US counterpart Donald Rumsfeld and "stressed the political problems the government was having with both MPs and the public."
An hour later Rumsfeld held a press conference and explained that Britain might not be involved in the invasion.
The media spin at the time was that Rumsfeld was speaking hypothetically, but according to a senior aide to Blair "Rumsfeld was telling the truth."
The government was thrown into panic. Blair "went bonkers," according to Campbell.
In his book The End Of The Party Andrew Rawnsley notes that the government's predicament was so serious that chief foreign policy adviser David Manning, aide Sally Morgan and foreign secretary Jack Straw "made further attempts to persuade Blair to pull back."
As we all know though, Blair didn't pull back.
But while the anti-war movement couldn't stop the war, Rai argues that the increased public scrutiny provided by the British and global anti-war movements may have reduced the destruction caused by US and British forces.
In addition to influencing the tenor of the invasion and the length of the occupation, February 15 2003 and the broader anti-war movement has had numerous long-term influences on the political landscape.
Here are just two examples.
Rai argues the march "was one of the most effective anti-terrorist actions of the last 10 years."
Why? Because "it convinced a whole bunch of people that Muslim concerns and Muslims as people in the Middle East were of value to large numbers of people in the West."
Then there are the hundreds of young people who were politicised and radicalised in 2003, many later becoming involved in direct action groups such as Plane Stupid, Climate Rush and UK Uncut.
"We are the Iraq generation," Joss Garman, a founder of Plane Stupid, told me. "You'd be hard-pressed to find somebody involved in the climate direct action movement who wasn't influenced in their politics and their choice of tactics by the whole Iraq debacle."
The novelist Milan Kundera argues: "The struggle of man against power is the struggle of memory against forgetting."
It is essential then that we remember and celebrate the record-breaking popular protest against the attack on Iraq.
Far from being ignored, the anti-war movement was a key influence on the government in the run-up to the war and during the invasion and occupation. As the famous US peace activist Dave Dellinger once said, "We have more power than we know."
With Prime Minister David Cameron recently warning that the so-called terrorist threat will require a response lasting "decades," we may well need to take to the streets again in the near future to stop the next war.
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