Image copyright EPA Image caption Parkland students Tyra Hemans and Emma Gonzalez at the March for Our Lives Rally in Washington, DC

The attacks on survivors of the school shooting in Parkland, Florida began almost immediately. Within hours, they had been accused of being "crisis actors" - an old conspiracy theory, recycled from previous school shootings, that claims survivors are actors parachuted in to promote gun control.

In the weeks since the 14 February shooting, a group of Parkland survivors has really taken on the mantle of advocating stricter gun control, culminating in a massive march in Washington DC on Saturday and hundreds of others across the country. Their efforts have brought them a huge new public profile, and with it a wave of personal attacks.

David Hogg, 17, and Emma Gonzalez, 18, are two of the most prominent among the young activists. In the week after the attack, Hogg was forced to deny that he had been coached by his father, a former FBI agent, on what to say. This week, the right-wing blog Breitbart published a round-up of tweets falsely suggesting Mr Hogg performed a Nazi salute at the march in Washington. The prominent right wing personality Alex Jones took footage of Mr Hogg speaking at the march and dubbed it over with a speech by Hitler.

Ms González was subjected to a viral video, doctored to show her tearing up the US constitution. In fact, she was tearing up a gun target. She has also been attacked by a Republican congressman for wearing a Cuban flag patch - her father is Cuban - and by a Republican state house candidate for her appearance - a "skinhead lesbian".

Media playback is unsupported on your device Media caption Emma Gonzalez demonstrated the power of silence during her speech

In the days after the shooting, in which 17 people died, it was easy to assume the fallout would follow a similar trajectory to previous school shootings. Thoughts and prayers, some calls for reforms, and then a swift return to the business-as-usual politics of gun control.

After the 2012 shooting at Sandy Hook Elementary School in Connecticut, which claimed the lives of 20 children and six staff, there was similar outrage, similar conspiracy theories, similar attacks on survivors, and calls from then-President Barack Obama for gun reforms. Then nothing happened.

But from the aftermath of the Parkland shooting, Mr Hogg, Ms González and a handful of their classmates have galvanised a national, youth-led movement that has not faded from the front pages. Young, idealistic, and marching in memory of murdered classmates, they present possibly the greatest PR challenge the NRA has ever faced.

Some conservative commentators felt unfairly hamstrung in criticising the students because of their age. "[Y]ou are not allowed to disagree or you are attacking the child," complained Fox News host Tucker Carlson, in an interview with NRA TV host Dan Bongino. Mr Carlson went on to suggest the students were being used by "organised anti-gun groups" in a "kind of moral blackmail".

CNN political commentator Jack Kingston said he didn't believe high-school students could have organised the rally in Washington, accusing them of being "hijacked by left-wing groups" with an "anti-gun agenda".

Others were more direct in their attacks. The campaign team for Republican congressman Steve King criticised Ms González for wearing a Cuban patch. "This is how you look when you claim Cuban heritage yet don't speak Spanish," he wrote on Facebook, "and ignore the fact that your ancestors fled the island when the dictatorship turned Cuba into a prison camp, after removing all weapons from its citizens; hence their right to self-defense." (Others pointed out on Twitter that the Cuban flag predates Communist control of the country.)

"She's a beautiful woman of Cuban descent and we love her. You would too if you ever got the chance to meet her," tweeted Mr Hogg in response.

Leslie Gibson, a Republican candidate for the Maine state legislature, called Ms González a "skinhead lesbian" and Mr Hogg a "moron" and a "baldfaced liar." She dropped out of the race shortly after.

Media playback is unsupported on your device Media caption 'Our message to the world is...'

The fringe Conservative media took things a step further, with blogs like Breitbart and Infowars publishing tweets likening Mr Hogg to Hitler. It was Infowars' Alex Jones, in the wake of the Sandy Hook massacre, who claimed the shooting has been staged by the government and accused the parents of being actors.

But there was a new tactic, too - one that some see as the future of fake news: doctored video.

Footage of Ms González tearing up a target was digitally altered to appear as if she were ripping the constitution. It was shared by the actor Adam Baldwin to his 271,000 followers, and by the right-wing social network "Gab" to its 100,000 followers with the caption "Not gonna happen".

The doctored footage was designed to tap into a fear among gun advocates that the students would press lawmakers to repeal the Second Amendment entirely. Writing in the New York Times, retired Supreme Court Justice John Paul Stevens called on the students to demand just that. But so far, they have called only for a raft of "commonsense" gun reforms such as higher minimum purchasing ages, improved background checks and a ban on assault rifles. No-one has torn up the constitution.

In a sign that there may be more people prepared to counter the forgery than spread it, a post revealing that the video was doctored has now been shared many more times than the original fake.

But the idea that the Second Amendment itself is under threat is a useful propaganda tool. Infowars contributor and conspiracy theorist Paul Joseph Watson posted pictures of three protest signs from the march, apparently calling for total gun control, claiming they "betrayed [the march's] real agenda - the end of the Second Amendment, by force if necessary".

Another line of attack from Infowars, Campus Reform and other conservative sites has been to mock protesters over their inability to articulately define an "assault rifle" - a useful but already ill-defined term for the military-style rifles used in many mass shootings.

And there has been a strain of criticism that accuses the Parkland students, who appeared on a recent cover of Time magazine, of trading on the tragedy for publicity and social-media followers. On Fox News on Sunday, Colion Noir, a host on the NRA TV channel, told two Parkland students in the studio, Delaney Tarr and Cameron Kasky, that if a "good guy with a gun" had been in their school on 14 February "your classmates would be alive and no-one would know your names".

Remarkably composed, Ms Tarr disagreed with the idea that anyone apart from police should carry firearms in a school. Then Mr Kasky took issue with the other part of Mr Noir's claim. "They have no idea how much each of us would give for it to be February 13th again," he said.