In 1858, William Herndon, the law partner of Abraham Lincoln, did research in the Illinois State Library to collect "all the ammunition Mr. Lincoln saw fit to gather" to prepare for the run against Stephen A. Douglas in the 1860 presidential race [REF].
In the 1992 presidential campaign, Republicans reported that they spent $6 million on a "state of the art (opposition research) war machine" to investigate Bill Clinton, who was running against George H. W. Bush.