Democrats who had hoped to use Monday’s congressional testimony as an indictment of the war in Iraq found themselves on the defensive over an ad impugning a respected American general. MoveOn.org, a liberal advocacy group that has become increasingly influential within the Democratic Party, ran a full-page ad in Monday’s New York Times that pre-emptively dismissed testimony delivered later in the day by Gen. David Petraeus, commander of U.S. forces in Iraq. “General Petraeus is likely to become General Betray Us,†said the ad, which accused him of “cooking the books for the White House.†Petraeus insisted he wrote his...