In early 2016, while researching some of the most popular U.S. secession groups online, I stumbled across one of the Russian-controlled Facebook accounts that were then pulling in Americans by the thousands. At the time, I was writing on Russia’s relationship with American secessionists from Texas, Hawaii and Puerto Rico. These were people who had hitched flights to Moscow to swap tactics, to offer advice and to find support. They had found succor in the shadow of the Kremlin.

That was how I eventually found my way to the “Heart of Texas” Facebook page (and its @itstimetoecede Twitter feed as well). Heart of Texas soon grew into the most popular Texas secession page on Facebook — one that, at one point in 2016, boasted more followers than the official Texas Democrat and Republican Facebook pages combined. By the time Facebook took the page down recently, it had a quarter of a million followers.

The page started slowly — just a few posts per week. Unlike other secession sites I’d come across, this one never carried any contact information, never identified any individuals behind the curtain. Even as it grew, there was nothing to locate it in Texas — or anywhere else. It was hard to escape the suspicion that there might be Russian involvement here as well.

There were other oddities about the site. Its organizers had a strangely one-dimensional idea of its subject. They seemed to think, for example, that Texans drank Dr Pepper at all hours: while driving their giant trucks, while flying their Confederate battle flags, while griping about Yankees and liberals and vegetarians.

But Heart of Texas, sadly, was no joke. At one point the page’s organizers even managed to stir up its followers into staging an armed, anti-Islamic protest in Houston. As gradually became clear, this was part of a broader strategy. The sponsors of the page were keen to exacerbate America’s own internal divisions. At certain moments they lent support to Black Lives Matter, while in others they would play to the latent (or obvious) racism of Donald Trump’s base.

By the summer of 2016, other themes began to emerge. Posts began to follow a perceptibly hard-right course, stressing Texas’ status as a “Christian state,” or touting the Second Amendment as a “symbol of freedom . . . so we would forever be free from any tyranny.” Some of the page’s contributors talked about the need to “keep Texas Texan,” whatever that meant. There was also a generous dollop of conspiracy theory. There were posts about the allegedly unnatural death of Supreme Court Justice Antonin Scalia and the supposed federal invasion orders behind the Jade Helm military exercise. Fake Founding Father quotes mingled with anti-Muslim screeds and paeans to Sam Houston. And the number of followers steadily crept into the hundreds of thousands.

Though the site’s authors understood their audience well, there was something off about their writing. The page’s “About” section proclaimed that “Texas’s the land protected by Lord [sic].” Grammatical and spelling glitches were everywhere: “In Love With Texas Shape,” “State Fair of Texas — Has You Already Visited?,” “Always Be Ready for a Texas Size,” “No Hypoclintos in the God Blessed Texas.” (Or take this caption for a photo of country music star George Strait: “Life is not breaths you take, but the moments that take your breth [sic] away.”) Yet the typos never seemed to raise any suspicions in readers’ minds.

Even the page’s calls for an early November protest across the state — part pro-secession, part anti-Clinton — were garbled. One post declared that “we are free citizens of Texas and we’ve had enough of this cheap show on the screen.” The site called on those who showed up to “make photos.”

Heart of Texas chugged on after the election, bringing in tens of thousands of new followers in 2017 who were unbothered by its mangled English, its rank nativism and its calls to break up the United States.

And then, in August, it was gone. Just like that, the most popular Texas secession page on Facebook was revealed to be a Russian front, operated by the notorious Internet Research Agency, with Facebook removing all of the posts from public view. (It’s worth noting that another Instagram account started posting Heart of Texas material as soon as the original Facebook page was taken down.)

Despite its claims of transparency, Facebook has effectively prevented the public from examining these posts and these pages. So far Heart of Texas remains the only example of a Russian account that I and other researchers managed to study in detail before Facebook pulled the rug out from underneath it.

We know that the Russians behind these sites played all of their readers, and especially those who showed up at its protests in places like Twin Falls and Fort Myers and Houston, for fools. Considering that the number of their combined followers ranged into the millions — with some estimates placing total views potentially in the billions — they’re probably right.

The creators of Heart of Texas not only targeted the sociopolitical tensions within the United Staes. They also exploited our gullibility, which turned out to be far greater than I could have ever imagined. And by assisting them in this massive lie, Facebook has enabled one of the greatest frauds in recent American history.

Casey Michel is a journalist based in New York.