A smoking gun. Allegations of fake news. Adversarial press coverage that made it impossible for embarrassed lawmakers to sweep a scandal under the rug.

The political sensation that came to be known as the Credit Mobilier scandal unfolded in the era of the telegraph and the steam engine. But it included elements of every Washington scandal, from Teapot Dome and Watergate to Whitewater and the allegations that the Trump campaign colluded with Russia.

The 19th-century scandal touched a breathtaking roster of luminaries, including Vice President Schuyler Colfax and future President James A. Garfield. Many of those involved denied any wrongdoing, only to be exposed as liars by congressional investigations.

The story began in the winter of 1868, three years after the South had surrendered at Appomattox and an assassin’s bullet had claimed the life of President Abraham Lincoln. Congress and Lincoln’s successor, Andrew Johnson, battled over Reconstruction and the rights of freed slaves. One attempt to impeach Johnson had failed; another would soon prove successful.

As Johnson and Radical Republicans skirmished, Rep. Oakes Ames (R-Mass.) was fending off the claims of a fellow railroad investor, who was pestering him for more shares in Credit Mobilier, the highly lucrative, oddly named construction subsidiary of the Union Pacific Railroad. ...