As president, Joe Biden has the supreme power to pardon criminals at will, and he has wielded that power for a large number of convicted Americans. But it turns out that Biden has quite another connection to the presidential pardon, one dating back to the Civil War. According to The Washington Post, this sordid bit of Biden family history lay hidden for 160 years among hundreds of court-martial cases in the National Archives until it was recently uncovered by researchers. According to the researchers, Biden’s great-great-grandfather, Moses J. Robinette, was a civilian employee of the Union Arm…