Deana Schupp, a cable company worker from Florida, stared out over the huge crowd on Washington DC's National Mall and had a sudden but welcome realisation.

"When I see this crowd I feel I am not alone. We are here for sanity and there are a lot of us," she said. It was, she admitted, her first protest march.

She definitely had company. Over two hundred thousand people gathered here yesterday in what must surely be the strangest-titled mass protest ever held in America's capital: Rally to Restore Sanity and/or Fear.

It was the brainchild - or publicity stunt, performance art project or political expression - of the country's two leading satirists, Daily Show host Jon Stewart and Stephen Colbert, whose on-air persona of a right-wing buffoon lampoons the conservative media.

At first glance it looked like any other demonstration. But a few things were askew.

"Restore Sanity" declared large words. And of course the huge portraits of Stewart and Colbert - done up to echo the iconic Shepard Fairey image of Barack Obama - stared out bewilderingly over the masses.

It was an impressive display of the power of comedy and celebrity. Whether it was a display of the latent power of American liberalism was much harder to say.

Many observers saw the rally as a response to Fox News pundit Glenn Beck's recent "Restoring Honour" rally which occupied the same space several months ago. That event was seen as symbolising the rising power of right-wing conservatism.

But Stewart has vociferously downplayed any political intent. "This is not a political rally in any way, shape or form," he told Larry King last week. He has even dubbed it the "one-million moderate" march. True to his word, many of those coming to the rally, including those who had travelled huge distances, agreed.

"I wanted to come here as a sort of plea for a more commonsense politics," said Jake Edmonds, a 23-year-old student who had made a 14-hour car trip from northern Michigan. His driving partner, fellow student Nick Budes, agreed. "The number of people here is a physical representation of what a lot of people think: that everyone needs to take it down a notch," he said, referring to what many see as the over-heated nature of American politics and media outlets.

Many of those attending wore costumes depicting Mad Hatter or Wonder Woman or the scary rabbit character from the cult movie Donnie Darko. Signs waved by the crowd read: "Team Sanity."

Stewart has rarely, if ever, been an advocate for any sort of concrete agenda or liberal politics. There was no real talk, for example, of the intricacies of putting healthcare reform into practice, withdrawing from Afghanistan, job creation or any one of dozens of liberal ideals from climate change to green jobs. His main display of high-minded idealism was centred on a plea for politeness and reason in America's heated political world.

Instead, the atmosphere was one of irony and humour; of mocking those in power, not seeking to replace them. That fits the role that Stewart and Colbert actually play the best. They are the court jesters at the palace of the real power players in America. Their job is to point out the hypocrisies of the great and the good, not to oust them.

"The message is incredibly unfocused. They tell us it is not political. We should believe them," said Professor Robert Thompson, a popular culture expert at Syracuse University.

That has been echoed by the Rally for Sanity's main cheerleaders in the media. Alexandra Petri, in the Washington Post, highlighted how her generation had swapped political activism for ironic mockery. "Call us Generation I. I for irony, iPhones and the internet ... sum up our lives in a phrase? The Importance of Never Being Too Earnest," Petri wrote in a piece full of sentiments that must have broken the ageing hearts of countless former 1960s radicals.

Jeff Cohen, a media professor at Ithaca College, saw the rally as saying more about the state of celebrity in America than anything else: "It is about seeing someone you really like for free."

If there was one group of people that the rally did take genuine aim at it was the American media industry. That has long been the true aim of much - if not virtually all - of Colbert and Stewart's comedy. They have relentlessly gone after the mainstream media, accusing it of laziness, elitism, pandering to power and generally holding it responsible for a dumbing down of American life.