Wireless War on the Western Front

Radio and the deadlock of 1914

According to historian Holger Herwig, airplanes like the one above were solely responsible for the French victory on the Marne in 1914, halting the German juggernaut short of Paris. My skepticism is based on the planes themselves. Early aircraft like that one picture above had less horsepower than your average lawn mower, and about the same size of gas tank, for an operational limit of maybe 30 miles range and a service ceiling less than one mile in altitude. It is unarmed, and the pilot has limited means of communication with the ground.

Herwig cites German sources to claim that French pilots flying these planes used wireless transmission for air-to-ground artillery direction from planes like this one. While that is not impossible, indeed it is unsurprising, it would unlikely for most of the aircraft flying at that time, given the weight of most radios and battery systems that were available in 1914. So I have my doubts about this narrative. Indeed, it obscures the crucial role of other intelligence in directing the aerial observation. Consider the opening week of the campaign, when French pilots flew into Belgium looking for Germans without knowing where to look and consistently failed to find them.

After the disastrous contact battles that followed, French armies retreated to the Marne, where they formed a new defensive front. In doing so, they fell back onto their own lines of communication. As German divisions crossed through Belgium and into France, however, they left behind their telephone and telegraph lines and railways. Forced to unpack their radio sets, the Imperial German Army began producing lots of signal noise. Gen. von Kluck’s “missing” First Army first revealed itself to the DB by radio on 21 August. Furthermore, thanks to poor staff work and a combination of relentless pressure to advance, none of this traffic was encrypted. It was all en clair, perfect for exploitation by French military intelligence, the Deuxième Bureau (DB). They took full advantage.

We know the extent of French exploitation because Joffre’s men wanted us to know. In his “Memoir of the Battle of Ourcq River (5-8 September 1914),” published shortly after the Battle of the Marne, Joffre’s chief of staff Gen. Jean-Baptiste Clergerie told the entire world an amusing anecdote about poor German COMSEC practices:

General von der Marwitz, cavalry commander of the German First Army, made intemperate use of the wireless telegraph and did not even take the trouble to put into cipher his dispatches, of which the Eiffel Tower made a careful collection. In the evening of September 9th, an officer of the intelligence corps brought me a dispatch from this same Marwitz couched in something like these terms: "Tell me exactly where you are and what you are doing. Hurry up, because XXX."

The officer was greatly embarrassed to interpret those three Xs. Adopting the language of the poilu, I said to him: "Translate it, 'I am going to bolt.'"

Such a disclosure is rare today, but at the time it was quite normal for French politicians to disclose sensitive intelligence for whatever ends they had in mind. Still, we might ask what end justified this disclosure in a general’s mind, and I think a likely answer is that he wanted the DB to have a share in the public celebration of the ensuing victory on the Marne. The reader may already be familiar with the story of the so-called “Marne taxis,” a creative demonstration of the new importance of motorized transport in war that still did little to win the actual battle. It is merely the most famous example of the jubilant triumphalism that followed the Marne; Clergerie just added one more congratulatory press release to the pile. It is to Joseph Joffre’s discredit that he ignored this intelligence at first, only coming to rely on the DB after his cavalry commanders proved unreliable in Belgium. Perhaps the “attaboy” was compensation for Joffre’s earlier mistake.

Lt. Col. Francois Cartier supervised the construction of radio direction-finding stations. He led the Bureau du chiffre (BC) within the Section de renseingments, which was already quite accomplished at cryptography. None of Germany’s codes proved particularly difficult to crack during the war, and when London entered into strategic intelligence-sharing arrangements with Paris, they learned as much as they taught about deciphering German transmissions.

Thus in Barbara Tuchman’s Guns of August, we find the “historical novelist” putting Clergerie into her scene with Col. Pierre Girodon, a hero of the colonial war against the tribes of the Moroccan interior who is recovering from his wounds. Working in a chateau, they analyze streams of information coming from a variety of sources. Prisoners are interrogated. Dispatches, maps, and other documents are captured and read. All of this humming intelligence activity required a large staff with centralized organization and smooth communications — human infrastructure capable of rapid processing, transmission, and analysis. Tuchman’s dramatic scene ends with a pilot, sent out to check reports from other sources, landing his fragile machine in the field, then entering the chateau to report what he has found. This was “all-source intelligence analysis” a century before that buzzphrase was born.

And it is where the victory on the Marne was made.

Upon putting the last pin into a map of the Paris approaches, Girodon and Clergerie approve of the picture taking shape: “They offer us their flank!” Tuchman wrote from contemporary accounts, such as Clergerie’s September 3rd memorandum explaining that “the German columns, after heading straight for Paris, were swerving toward the southeast and seemed to wish to avoid” the defensive belt around the French capital. His account of this observation crediting radio SIGINT was repeated in various press outlets, including a New York Times volume of current history in 1917. Although it is a bit dramatized, Tuchman is not far off from what intelligence activity really looks like, whatever her shortcomings as a historian, though she regretfully fails to make the link between signal and intelligence.

Such an oversight may explain why a later generation of historians deprecates or ignores the role of SIGINT in the Marne victory, giving all the credit to the pilots. I don’t mean to deride Herwig’s excellent book about the Marne here. Rather, his account of the battle is essential for understanding the role that radio played in German decision-making, the flip side of the same story.

Although communications were a key concern in their staff rides and exercises, the Imperial German Army was tardy in improving or training to use its existing radio equipment. Chief of Staff Helmuth von Moltke chose to stay at a castle several miles from his radio station as the first Germans entered Belgium. This was an institutional doctrine at work: Auftragstaktik, the traditional German command style in which subordinate unit commanders expected full leeway to execute their orders as they saw fit, unbothered by constant management from above. As his forces advanced towards the Marne, all the message traffic von Moltke received was triumphal: the French were always retreating in disorder, totally destroyed and defeated. Yet as the situation deteriorated in the first week of September, Moltke could not leave his radio room more than a few steps away, and the sudden turn of bad news caught him mentally unprepared. Agitating for updates, reports from corps commands that had stopped advancing unnerved him. Then an intercepted British wireless message, reporting their slow advance into the famous gap between Moltke’s First and Second Armies, finally panicked the stressed-out field marshal. Using his radio room, von Moltke ordered the entire German army to retire on the Aisne and dig trenches.

Subsequent to the Marne, the combatants redeployed in a series of flanking moves and countermoves all the way to the English Channel. On 1 October, the BD cracked a new double transposition cipher. The Germans had been tardy in distributing the codebooks — a pattern that would continue throughout the war — so the new encryption did not last long. Over the course of the war, new German codes would be cracked within a single day. Again, the DB provided crucial intelligence of German dispositions, and so the Western Front cohered as a continuous, ~430-mile long battle zone within five weeks of the Marne.

Thereafter, the Germans rebuilt their telephone and telegraph infrastructure, seeking a more secure mode of communications. It would take until 1916 for radio to gain real operational importance again in France, but the story of the wireless war had begun with the greatest stalemate in military history.

Herwig calls the Marne “the most significant land battle of the 20th Century.” He argues that Germany was denied the short and lively (kurtz und vives) war planned by Alfred von Schlieffen and forced into the protracted war of attrition they had wanted to avoid. What explains this defeat? Read as a narrative of radio history, Herwig’s book reveals that communication was the Achilles heel of the world’s greatest army. Earlier, Martin van Creveld argued that Moltke’s army had reached its logistical limits, but we could also say that Germany had reached the limit of their communications.

Germany did not have enough field radio stations: von Kluck’s First Army headquarters, commanding the crucial right flank element of the entire scheme, had only one, and it was subject to constant jamming from the Eiffel Tower. Not only did this impede their communications, it forced multiple repetition of messages, guaranteeing that French field radio operators would obtain perfect transcriptions of everything sent or received.

This, too, has been known to scholars for a century, but I think these facts suffer for not having a strong interpreter. Cable channel audiences want human stories, the kind of tale Tuchman was good at telling, and not dry explanations of cryptology or radio physics. Radio is invisible, after all. It does not go zoom or boom or pew-pew-pew. Electromagnetism does not even sputter overhead like an ungainly Blériot airplane. A radio just sits there, working or not, so that the entire interoperating system of systems needed to “combine arms” is either working or not, right along with the radio. Why would anyone care about this narrative of history?