They said they would engage in a filibuster that would prevent the completion of the electoral count until Inauguration Day came and there was no president. They vowed to congest the streets of Washington and prevent Hayes from being inaugurated. Democrats organized armed bands and threatening 'Tilden or blood,' said they would phyically put Tilden in the White House. There was real fear that war would break out. Then something happened.
Historians disagree on exactly what it was.
Some people believe that a compromise was reached at a hotel meeting between emissaries of the two parties. At that meeting, a deal was supposedly brokered that, among other things, stipulated that if Hayes became president, he would remove the remaining federal troops stationed in the South, effectively ending Reconstruction, a matter of great importance to Southern states. That did in fact happen, but whether it was a formal quid pro quo linked to Hayes' assumption of office is unclear. The end was at hand. He was a completely ineffective president.