Many historians and apologists for the US Army make different excuses for the US Army being caught completely unprepared for the German attack in the Ardennes in December 1944. This battle is known to the Germans as Wacht am Rhein and to the Americans as the Battle of the Bulge. It is the largest battle ever fought by the US Army.
The top excuse given for the Americans being totally surprised by this attack is that the Germans didn’t communicate orders for Wacht am Rhein by radio. Orders were sent by hand of officer or secure land-line teletype. Since we had no messages to pick out of the air and decode, we were consequently surprised. But there was no reason for SHAEF to be surprised except hubris. (SHAEF: Supreme Headquarters Allied Expeditionary Forces — the formal name for the Anglo-American command in Europe.)
While there was a blanket of operational security over the planned attack, no one in the German High Command told the Reichsbahn to use similar security procedures. Like all German organizations, the Reichsbahn — the German national railway — used a version of the German enciphering machine known as Enigma to communicate, believing it secure. But their enciphering protocols were lax, breaking into their ciphers wasn’t difficult and we read most of their radio traffic during the war. Moving the men and equipment from Germany and Russia to the Ardennes, required the massive use of trains and massive use of trains required lots of coordination — which required lots of radio messages. Reichsbahn dispatchers had to tell various divisions where to assemble and when to embark on the trains allocated to them. It took as many as 40 to 50 trains or more to transport one armored division. We were reading this radio traffic and knew the Germans were engaged in a buildup of their forces. Front line units also reported new German formations appearing on their front. Somehow this information just didn’t get the priority or attention it should have.
Our top echelons did not believe that the Germans could, or would, attack through the Ardennes forest although they had done so at the beginning of the war and had surprised the French. Helmuth von Moltke the Elder, one of Prussia’s greatest military thinkers purportedly said:
Meaning, he will do something completely unpredictable. We forgot this to our peril and lots of American and Allied soldiers died who need not have. One of them was the father of a friend of mine.