This operation was the brainchild of German dictator Adolf Hitler, and consisted of using specially-trained German soldiers in captured Allied uniforms and vehicles to cause confusion in the rear of the Allied defense. A lack of transport aircraft, uniforms and English-speaking soldiers limited this operation, but the confusion it created went well beyond Hitler's, and Skorzeny's, wildest dreams.
About two dozen German soldiers, most of them in captured American army Jeeps, got through the lines in the initial confusion of December 16, 1944 and began changing signposts and creating panic among American troops they encountered.
However, some of the saboteurs were captured by the Americans. Because they were caught in American uniforms, their interrogators threatened to execute them unless they divulged their mission. Knowing they were likely to meet that fate anyway (they did), the Germans falsely told the Americans that their mission was to go to Paris to either kill or capture overall Allied commander General Dwight D. Eisenhower. They truthfully told the interrogators that Skorzeny was their commander.
The Americans had already captured some documents referring to Operation Greif--the German word greif translating to "seize" in English. Because Skorzeny was already well-known for rescuing Italian dictator Benito Mussolini and kidnapping the son of Hungarian regent Miklos Horthy, the Americans were more than willing to believe Eisenhower was his next target.
Because of the perceived threat, Eisenhower was confined to his headquarters for several days, and thousands of American MP's were put to work trying to hunt down Skorzeny's men.
Ironically, the overall mission was regarded by Skorzeny as a failure. Because a total breakthrough wasn't achieved on the first day of the battle, Skorzeny had to use most of his panzer brigade as ordinary combat troops, in German uniform.
After the war, Skorzeny was tried by the Allies as a war criminal for allowing his men to fight in enemy uniform. He was acquitted when a British commando testified in his defense that he had done the same thing.