Early Tuesday morning, as protests continued to embroil the city of Ferguson, Missouri, a ragtag troupe of civilians equipped with camouflage tactical vests, body armor and tricked-out assault rifles swaggered onto the scene. They identified themselves as members of the Oath Keepers, a grassroots “patriot” organization established in 2009 to “defend the Constitution against all enemies, foreign and domestic.” The group claims to have more than 30,000 current U.S. military service members, veterans, first responders and police officers in their ranks. Though, on this particular occasion, only a handful appear to have answered the call of duty. While the Oath Keepers insist that they’ve come to the St. Louis suburb to serve and protect, the St. Louis County Police Chief Jon Belmar called their presence "unnecessary and inflammatory." So who are these goatee'd vigilantes? Here’s what we know.

The Oath Keeper's founder cut his teeth in the military. Founder Elmer Stewart Rhodes (pictured above), an ex-U.S. Army soldier who was honorably discharged from the service after suffering a spinal injury during a training exercise in the late ‘90s. There is no evidence to suggest that Rhodes himself has ever experienced combat. That, however, hasn’t kept him from urging others to take up arms against the group’s perceived enemies. “Go armed, at all times,” he recently wrote on the Oath Keepers website, “as free men and women, and be ready to do sudden battle, anywhere, anytime, and with utter recklessness.”

Rhodes is an Ivy Leaguer. Following his military service, Rhodes attended the University of Nevada and graduated in 1998. After graduating from Yale Law School in 2004, he clerked for Arizona Supreme Court Justice Michael D. Ryan. In 2008, Rhodes volunteered on libertarian Ron Paul's presidential campaign.

Rhodes is scared of America becoming a police state. In a 2008 article published in S.W.A.T. Magazine, Rhodes referred to Hillary Clinton as “Herr Hitlery,” warning that if she were elected president Clinton would sign a ban on the private possession of firearms while wearing “her favorite Chairman Mao signature pantsuit.” Rhodes wrote a gun-rights column for the magazine called "Enemy at the Gate." The Oath Keepers website boasts a list of ten orders they will not obey. These include a refusal to obey "any order to disarm the American people," "any order to force American citizens into any form of detention camps under any pretext," and "any order to blockade American cities, thus turning them into giant concentration camps."

The Oath Keepers have around for six years. Rhodes founded the Oath Keepers in March 2009. "The whole point of Oath Keepers is to stop a dictatorship from ever happening here," Rhodes told the Las Vegas Review-Journal in October of that year. "My focus is on the guys with the guns, because they can't do it without them."

Oath Keepers have had trouble with the law before. In 2010, a 31-year-old Ohio man named Matthew Fairfield, a self-described Oath Keeper, was sentenced to 16 years in prison for the alleged possession of a live napalm bomb. In 2011, Darren Huff, a native of Georgia and a self-described Oath Keeper, was convicted of a federal firearms charge after allegedly plotting to raid a Tennessee courthouse in an attempt to force President Obama out of office. And in 2012, Charles Dyer, another self-described Oath Keeper, was found guilty on one count of child sexual abuse - for the rape of his own 7-year-old daughter - and sentenced to 30 years in prison.

Rhodes staged a protest in Arizona a few years ago and all he got was a lousy $600 fine. In 2011, Rhodes led a small group of Oath Keepers into Quartsite, Arizona to protest the ejection of local residents from a 2010 town hall meeting. Rhodes also wrote a "notices of claim" on behalf of two of the people ejected, and the State Bar of Arizona later admonished him for practicing law in the state without a license, and he was fined $600.

This isn't the Oath Keepers first rodeo. During the 2014 protests in Ferguson, Oath Keepers patrolled rooftops in an effort to protect local businesses and residents until the St. Louis County Police Department asked them to stand down.

The group has long been monitored by civil rights organizations. The Southern Poverty Law Center, a legal advocacy organization that specialized in civil rights and public interest litigation, has labeled the Oath Keepers an “anti-government ‘patriot’ movement.”

They see themselves as protectors of a defenseless people. On Tuesday, John Karriman, an Oath Keeper, told an NPR reporter in Ferguson: "We're not a threat to anybody other than to those that would seek to usurp our Constitution and not afford people their life, liberty and pursuit of happiness. ... We're the sheepdogs that keep the rest of the flock safe." The same Keeper told the BBC that the organization had come to Ferguson "because the government promised to guard our people and they didn't."

Rhodes wants Sen. John McCain to be tried for treason. During a speech in May of this year (see video below), Rhodes called for Sen. John McCain, a former POW and decorated veteran of the Vietnam War, to be “hung by the neck until dead” for contributing to the “destruction of this country.”