He tried to argue that it was US troops who did the killing at Malmedy during WWII.
Crooks and Liars has the full story, and Keith Obermans's correction of his factual misstep.
What a clown, without Faux News he would be unemployable.
Oh, and to make this a perfect example of what Bill O'Reilly really is, when he was call on this lie, he lied again, and claimed that he never said that, but was referring to later events inspired by the initial mass murder.
Unfortunately for him, it is all on tape, and what he said is very clear.