On August 17, 1998, President Bill Clinton becomes the first sitting president to testify before the Office of Independent Counsel as the subject of a grand-jury investigation.

The testimony came after a four-year investigation into Clinton and his wife Hillary’s alleged involvement in several scandals, including accusations of sexual harassment, potentially illegal real-estate deals and suspected “cronyism” involved in the firing of White House travel-agency personnel. The independent prosecutor, Kenneth Starr, then uncovered an affair between Clinton and a White House intern named Monica Lewinsky. When questioned about the affair, Clinton denied it, which led Starr to charge the president with perjury and obstruction of justice, which in turn prompted his testimony on August 17.

After testifying, Clinton addressed the nation live via television and gave his side of the story. He admitted to an inappropriate relationship with Lewinsky and said that he regretted misleading his wife and the American people when he denied the affair earlier. He insisted that he had given “legally accurate” answers in his testimony and that “at no time” had he asked anyone to “lie, hide or destroy evidence or to take any unlawful action.” In addressing the investigation into his past business dealings, Clinton insisted that the investigation did not prove that he or his wife Hillary had engaged in any illegal activity.

The damage, however, was already done. Revelations from the investigation sparked a battle in Congress over whether or not to impeach Clinton. While Democrats favored censure, Republicans called loudly for impeachment, claiming Clinton was unfit to lead the country. In December 1998, the House of Representatives voted to impeach the president, but after a five-week trial in the Senate, Clinton was acquitted. Public opinion polls at the time revealed that while many people disapproved of Clinton’s extramarital affair—which he conducted in the White House Oval Office—most did not consider it an action worthy of impeachment or resignation.

READ MORE: Why Clinton Survived Impeachment While Nixon Resigned After Watergate