Abraham Lincoln pardoned Biden's great-great-grandfather: Report

Abraham Lincoln pardoned Joe Biden's great-great-grandfather after a late-night Civil War-era brawl, documents reportedly show, linking the two US presidents across the centuries.

The court martial records in the US National Archives, reported on by the Washington Post Monday, detail the trial of Moses J Robinette after a fight with fellow Union Army civilian employee John J Alexander on March 21, 1864.

Robinette was charged with attempted murder after the tussle in the Army of the Potomac's winter camp in Virginia, when Alexander overheard him saying something about him to a cook, and rushed at him.

The two men scuffled, and Robinette drew his pocketknife, leaving Alexander with several cuts before others intervened, according to the documents.

The 42-year-old, who had been hired by the army as a veterinary surgeon, insisted that Alexander "possibly might have injured me seriously had I not resorted to the means I did."

But military judges convicted him and sentenced him to two years' hard labor.

Three army officers petitioned Lincoln to overturn his conviction, claiming the sentence was unduly harsh and that Robinette had been defending himself against someone "much his superior in strength and size."

Lincoln agreed, and signed the pardon on September 1 that same year.

The story "has waited 160 years to be told," according to the Washington Post article, written by historian David J Gerleman.

The "slender sheaf of 22 well-preserved pages of his trial transcript, unobtrusively squeezed among many hundreds of other routine court-martial cases in the National Archives, reveals the hidden link between the two men -- and between two presidents across the centuries," Gerleman wrote.

"Those few pages not only fill in an unknown piece of Biden family history, but also serve as a reminder of just how many Civil War stories have yet to be told."