Men wearing camouflage shirts began building a makeshift defensive camp outside the Capitol on Wednesday afternoon. They moved barricades and green fencing into a circle, and then pulled helmets from a crate and donned goggles in preparation for a clash that had been brewing for weeks and, arguably, for years on far-right forums devoted to President Trump.

TheDonald.win, that’s where it’s at,” said one of the men, referring to the website where defiant talk, conspiracy theories and tips on how best to lay siege to Washington have grown since Trump lost the Nov. 3 election.

Trump supporters overtook Capitol Police officers to enter the building as lawmakers attempted to count the electoral college votes on Jan. 6. (The Washington Post)

The comment underscored the potent, interactive role between the online and offline worlds in Wednesday’s breach of the Capitol. Violent talk on far-right forums fomented violent real-world action, which was then captured by smartphones, uploaded and celebrated on the same forums. The boundaries between the digital and analog all but disappeared as rage, provocation and gloating bounced back and forth, again and again.

TheDonald, as the camouflaged men at the Capitol suggested, offered a particularly vivid view of this combustible dynamic. The forum, banned last year from Reddit for hate speech and violent talk and now turned into a website, had been one of many online staging grounds for Wednesday’s riot, and the success of the takeover of the Capitol spurred celebration and calls for further action, including the execution of leading Democrats. For days before, the forum had featured advice on how best to sneak guns into Washington, despite its strict weapons laws.

By Thursday morning, though, different moods had set in on this and other pro-Trump forums. Anger and gloating were still there, but so was unease at the furious public and political backlash against the events of the day before, which led to dozens of arrests and left one person fatally shot by police and three people dead after medical emergencies. Some posters worried their favorite forums, including TheDonald, would get knocked offline by chastened Internet service providers. There also was a pitched effort to redirect blame against left-wing activists, such as antifa, for somehow dressing up as marauding Trump supporters — a claim that was obviously ridiculous to anyone who watched the events unfold on their televisions, computers or smartphones.

On TheDonald, as users argued that the removal of some violent comments suggested the site’s leaders had been “compromised,” one moderator wrote, “What do you want? Us to try to lead a [expletive] revolution … from a forum on the internet, which ends up getting the site shut down in a matter of days and all of us sent to the gulag?”

Many things born on the darkest corners of the Internet found their way to the heart of American democracy on Wednesday. Ludicrous claims among adherents of the QAnon conspiracy theory — including that leading Democrats are satanic pedophiles — got shouted by the mobs taking over the Capitol. The emerging garb of the far-right — camouflage, goggles, American flags draped as shawls — leaped directly from the far-right memeworld into the nation’s capital.

Years of social media comments about “lynching” political leaders opposed to Trump, meanwhile, manifested themselves as an actual noose, hanging from a makeshift gallows on the Mall. Someone wrote “BIDEN,” in reference to President-elect Joe Biden, on the wooden structure, with an arrow pointing toward the noose.

It was not clear if TheDonald or any similar pro-Trump forum directly coordinated the takeover of the Capitol, or if posters simply shared general advice, promotion and celebration of the idea of thronging to Washington in support of the president. Much of that was included in a popular thread called “PATRIOTS STORM THE CAPITOL | WATCH PARTY.”

The resulting mayhem appeared to proceed without obvious leaders, a common feature of political action developed and coordinated online, said Rita Katz, executive director of SITE Intelligence Group, which tracks political extremism.

“It’s a new age of terrorism that can’t exist without the Internet,” Katz said. “Having said that, the movement has a spiritual leader, which is Trump.”

Advance Democracy, a group headed by former FBI analyst and Senate investigator Daniel J. Jones, who led the review of the CIA’s torture program, also was tracking pro-Trump forums as they built toward Wednesday’s assault.

“In the lead-up to yesterday’s violence, the Capitol rioters needed a place to plan for how the violence would unfold. They found this on unmoderated pro-Trump forums such as TheDonald.win,” Jones said. “There, they posted their plans to take matters into their own hands and literally threatened to kill lawmakers. They encouraged each other to bring illegal weapons. When this came to fruition, the real-life actions provided fodder for those on the forum.”

In the aftermath, pro-Trump forums wavered between glee, deflection and recrimination, shunting blame for the chaos onto a mass of scapegoats. They blamed Vice President Pence, for not subverting the reality of Trump’s loss, and old foes like Democrats, the media and the “deep state.” They also blamed the Capitol Police and other members of law enforcement.

Some pro-Trump posters conjured new conspiracy theories to explain away the damage: “Does anyone else feel like this was all a complete setup?” conservative commentator Evan Kilgore tweeted late Wednesday, in a message that was “liked” more than 114,000 times.

Social media sites like Facebook and Twitter worked belatedly to tamp down some of the fervor. Facebook indefinitely suspended Trump‘s accounts Thursday, while Twitter blocked him from tweeting for 12 hours. A number of less-moderated alternatives offered refuge for Trump supporters eager to egg the chaos on.

The pro-Trump attorney L. Lin Wood, whose Twitter account was suspended Wednesday after he baselessly accused Pence of being a “child molester,” leaped quickly to the alternative social network Parler, where he urged Trump-supporting “patriots” to keep fighting, saying, “Almighty God is with you. TODAY IS OUR DAY.”

“Get the firing squads ready. Pence goes FIRST.” Wood wrote in a Parler post that has been directed toward user feeds nearly 3 million times.

TheDonald, Wood and Parler did not respond to requests for comment.

Parler positions itself as the "free speech" alternative to Twitter and Facebook. And after the 2020 election, conservatives welcome that. (The Washington Post)

Seeing the chaos as a marketing opportunity, extreme right-wing groups used encrypted messaging services to coach their followers on recruitment strategies for winning newly disillusioned Trump supporters to their cause.

One self-identified neo-Nazi account wrote to more than 7,000 followers on Telegram, advising them that many people normally averse to a violent ideology could now be more vulnerable to radicalization.

“It will soon be the time to start individually reaching out to Rightwing types and spreading our ‘There is No Political Solution’ message,” the account said.

Another white supremacist “fraternity” discussed the possibility of a White-led uprising after Wednesday’s attempted insurrection. “Your mission is to invite [Trump supporters] into our spaces. Tell them there is a solution to their problem. Invite them to telegram. Seize the opportunity,” the administrator posted. “I’m sure a lot of them lost faith with [Trump] today,” one commenter responded.

On TheDonald, where users had proudly shared their travel itineraries for Wednesday’s demonstrations and planned meetups at hotels and restaurants near the White House, the triumphant mood quickly soured after Pence refused to intervene, with thousands of commenters labeling him a criminal traitor compromised by the “swamp.”

Even as they posted, their real-world compatriots tore through the Capitol building voicing the same anger. “Where's Pence, show yourself!” one rioter said after barging onto the Senate floor.

When Trump tweeted a video asking protesters to return home, a barrage of posts ripped through the forum expressing a mix of disbelief and frustration.

“HE ASKED US TO COME. ‘JAn 6 WILL BE WILD,’ ” wrote the user “RiverFenix” in a post quoting Trump’s tweet from last month. “IM AM SO CONFUSED SOMEONE SHAKE ME AWAKE,” the account added.

While some posters expressed continued allegiance to the president, many others responded with cynicism. “Let’s move on to someone that will actually fight and isn’t afraid of scrutiny,” one user commented. “He led us to slaughter,” said another.

Still, a contingent of Trump supporters and believers in the QAnon conspiracy theory voiced the belief that the siege was all part of a plan to keep Trump in power — and that more tumult would come in the days ahead.

“Sleep well tonight patriots. … You are going to love how this movie ends,” wrote “StormIsUponUs,” a QAnon-espousing account with more than 450,000 followers on Parler. “'Nothing can stop what’s coming’ wasn’t just a catch-phrase.”

Michael E. Ruane contributed to this report.