The wrong password.
One team put the US headquarters on high alert with a single sentence. On December 17 a jeep was stopped at Aywaille. The occupants did not know the correct password. According to their papers, they were 'Charles W. Lawrence', 'Clarence van der Wert' and 'George Sensenbach'. They confessed to being German infiltrators belonging to a huge unit operating behind the lines of the Americans. Their actual names were Günther Billing (21), Manfred Pernass (23) and Wilhelm Schmidt (24). And then came the phrase that would fill the US military with deep fear. Wilhelm Schmidt told his interrogators that a unit of 200, no 300 paratroopers were on their way to Paris to capture Eisenhower. The US military went into a paranoid state. Passwords were no longer trusted, the strangest questions were asked when blocked, 'What was the name of President's Roosevelt's dog?', 'Who was Betty Grable married to?', and the necessary questions about baseball! Two American soldiers were killed in a roadblock by their own fire because of these infiltrations by Skorzeny's commandos. Eisenhower was forced to leave his villa outside of Paris and was placed under house arrest at his Versailles headquarters, driving him mad.
Schmidt, Billing and Pernass minutes before their execution
The three German 'Americans' were executed as spies behind the American barracks at Henri-Chapelle on December 23. While the other two met their fate in silence, Gunther Billing invoked his Fuehrer. After the war, the three spies were buried, along with 39,000 other German soldiers, in the military cemetery in Lommel.