This is referring to the “1879 Rider Wars”.

This was an attempt by Democrat lawmakers to disenfranchise Black voters ahead of the 1880 election by threatening to defund the government. It resulted in the first US government shutdown.

In short, Democrats attached riders to appropriation bills in 1879 which would have removed Federal supervision of elections and made it illegal for Federal troops to guard southern polling places. Given the widespread use of intimidation, violence, kidnapping and murder to keep Black voters and Southern republicans from the polls, this would have been effective disenfranchisement.

Democrats controlled the House and the Senate and threatened to strangle all funding to the government if the Republican President Randolph Hayes vetoed their bills.

Hayes called their bluff and vetoed the bills for 14 months, which led to a partial shutdown of the US government. “The new doctrine, if maintained, will result in a consolidation of unchecked and despotic power in the House of Representatives,” Hayes said in his first veto message. “A bare majority of the House will become the Government.”

Eventually public opinion swung against the Democrats and they abandoned their plans. The Republicans won both houses of Congress and the White House in 1880.

While I am a big fan of HCR, and - hopefully obviously - very much opposed to disenfranchising Black voters, I think it goes too far to say that this was an attempt to dismantle the Federal government. If it had been successful it would have skewed the power towards congress, but it’s not like they were proposing an alternative model of government.

HCR wrote about this in one of her July letters, but unsurprisingly it is heavy on the modern parallels (which are interesting, but not really in the spirit of this sub): https://heathercoxrichardson.substack.com/p/july-2-2021

If you want a more purely historical account then the US House of Representatives has a good summary here: https://history.house.gov/Historical-Highlights/1851-1900/1879_rider_wars/

This is a bit of a mystery. There are a few moments where the federal government was really in danger, and some of them do get little attention (like the Presidential election of 1800, when John Adams and a Federalist congress willingly ceded power to the winning Thomas Jefferson, instead of refusing to certify his election.)

The only thing that is even vaguely this, in 1879, is the ending of the 1870 & 1871 Enforcement Acts that had protected the civil rights and voting privileges of African Americans, and gave the Federal government the power to intervene with force to do so. Under U.S. Grant the government had intervened, sending in troops and doing a lot to clamp down on terrorist groups like the KKK. In 1879 the Democratically-controlled Congress refused to allocate money for the Federal marshals that were very important to that effort, and enforcement completely ended. However, this was just a last step in the erosion and dismantling of Reconstruction that had been happening for several years, as southern Whites regained power in their states and the Democratic party won elections. The most famous event in this was the close Hayes-Tilden Election of 1876. The Democrat Tilden won, but the Republicans were able to "count" the votes in Congress, and there was a danger that a new sort of civil war could break out. So, a bargain was struck- Hayes would get the Presidency, but Reconstruction would end. Most people think of that bargain as the moment when the Whites in the North abandoned the Blacks in the South to their fate. But even before 1876, the Federal government had ended the Freedman's Bureau, and U.S. Grant had mostly stopped sending troops into the South.