The pastoral calm of the Warndt Forest in the Rhine Valley had been broken on September 7th, 1939; the soothing sounds of nature quickly replaced with the creak of tank tracks, the roar of trucks, and the stomping of men on the march.  Only three days earlier, Germany’s western frontier had become a potential battlefield as Britain and France had declared war over Berlin’s invasion of Poland.  For the second time in a generation, the Franco-German border would be a scene of intense conflict.

But the soldiers on the move were not members of the Wehrmacht.  Most of Germany’s border towns had been cleared of both soldiers and civilians with the coming of a Second World War.  These men were members of the French Second Army Group, part of 11 divisions and the opening wave of a planned 44 division invasion of Germany that would pull enemy forces away from a beleaguered Poland and dive deep into Germany’s industrial core.  In all, the Allies had an estimated 110 divisions they could turn against Germany while the Nazis had, at most, 22 undermanned divisions to repel any such attack.

A week into the Second War World, France was in German territory.  The outcome of the conflict rested on Paris and London’s willingness to stay on the offensive.

A French soldier inspects a German poster in the Saarland during the French invasion of Germany

In some respects, September 7th, 1939 was a date that France had planned on for 20 years.  

Since the end of the Great War, military and political leaders in both France and Britain had sought to emulate an “Entente-lite” coalition to box in Germany in the event of a future conflict.  While an alliance of new, smaller nations like Czechoslovakia and Poland could hardly match the industrial output and manpower of a Tsarist-era Russia, any tangible military threat in the east would ensure that if another conflict began, Germany would again find itself gored on the horns of a two-front war.  To cement such a position, Czechoslovakia, Romania and Yugoslavia would form the “Little Entente” with French oversight, while Paris signed a direct defensive alliance with Poland in 1921.  The French-Polish Treaty assumed that France would take offensive action against Germany within three days of starting mobilization while launching a full-scale assault within 15 days, presumably while Poland would fight any rearguard action to buy time. 

The terms of the “Little Entente” and the Franco-Polish alliance would not survive political and logistical realities.  The “Little Entente” had intended to ward off any revival of the Austro-Hungarian Empire, or more specifically, to prevent rearmament and expansion of then present-day Austria or Hungary.  Germany’s Anschluss with Austria and burgeoning alliance with Hungary started the process of ending such considerations – Yugoslavia would become dominated by pro-German politicians following the assassination of King Alexander I and Czechoslovakia would be betrayed at Munich and eventually bloodlessly conquered.

British soldiers eat and wait for their turn to fight

As for the Franco-Polish alliance, the treaty assumed that France could quickly assemble their troops and mount a decisive offensive.  In reality, the speed of World War II mechanization could vastly outstrip France’s World War I-styled mobilization.  The five million Frenchmen that would be called to arms would still be mailed their mobilization cards, taking days or even weeks to arrive.  Worse, with prioritization given to assembling men, the task of clothing, feeding and arming those men became secondary – thousands of mobilized French soldiers sat waiting for uniforms, boots and guns.  Britain wasn’t any better.  The British Expeditionary Force delivered four divisions within a month of the war beginning, but this force was far from a modern armored or mechanized army.  And once arrived, few reinforcements came from across the channel.  From October 1939 until the end of the year, only one more British division came to fight on French soil. 

The heart of the treaty – a French strike into Germany – also seemed to contradict key elements of France’s intra-war strategic planning.  While the construction of the maligned Maginot Line would develop a post-war narrative that France only had a defensive war plan, the Allied strategy did strongly rest on being reactive versus proactive.  Any offensive against Germany would inevitably take place along the relatively narrow front of the French-German border, as Belgium and Holland’s strict neutrality meant that a flanking attack through those countries was politically impossible – Paris was not going to preemptively invade their latent allies.  Thus, the Allied strategy rested on a presumed German invasion of Belgium, around the Maginot Line, where the French and British armies would then meet them and keep the carnage off of French territory.  An offensive into the Saar would by definition abandon that strategy, leaving the invading French armies potentially vulnerable to a German counterattack that might wheel around them through Belgium and cut them off (a version of which ultimately occurred in 1940). 

Nevertheless, the French were willing to meet at least the most minimal of terms of their alliance with the Poles – France went on the offensive.  

France’s declaration of war

As French tanks and troops crossed on a twenty-mile wide offensive across the border, they found few Germans and even less German action.  The most damage done to the invading Frenchmen were from mines, not German soldiers.

Instead, they found posters bearing printed messages such as: “French soldiers, we have no quarrel with you. We shall not fire unless you do.”  Germans vans with speakers blasted similar propaganda messages.  France even continued receiving an uninterrupted supply of electricity from German power plants in the Saarland.  Neither side seemed overly invested in the war – a single German machine gun unit managed to hold up the entire invasion for a day as troops on both sides went through the motions, cautiously avoided trying to hit one another.  The entire offensive read more like the last hours of the prior Great War, with combatants unwilling to fight, than it did the first hours of next World War.

While the French position may have spoken of their morale, the German position was one of strategic necessity.  90% of the Luftwaffe and practically 100% of Germany’s armored and anti-tank units had been committed to the Polish invasion.  A meager 22 divisions were available to counter any French offensive and those present in the Saarland found their units little match for French armor and artillery – German anti-tank projectiles harmlessly bounced off of the French Char B1 tanks.  The Germans hoped to stall for time, slowing any advance and then retreating behind the Siegfried Line – Germany’s response to the Maginot Line, with18,000 bunkers, tunnels and tank traps.  The French would halt their advance after five miles, just in sight of the Siegfried Line, unwilling to directly assault the position, fearful that an attack would merely grind their men and material against the line in a First World War fashion.  France’s commander-in-chief, General Maurice Gamelin, defended the decision to halt by declaring “I shall not begin the war by a Battle of Verdun.”  

Maurice Gamelin

The decision to stop had come following the first Anglo-French war council as both France and Britain decided that they were ill-prepared for a continued attack, especially one against a prepared defensive position like the Siegfried Line.  By September 12th, the war in Poland looked to be over – all of Poland west of the Vistula had been conquered except for the isolated Warsaw, and Polish forces were in a headlong retreat to the Romanian border to make a desperate last stand.  Gamelin had once confidentially predicted that the Poles could at least hold out for six months alone; they now looked as those they might surrender within another week.  Any invasion of West Germany now seemed a fruitless act.  And the Allies would compound the matter by refusing to attack German industry by air (Gamelin vetoed even RAF strikes over concern about counterattacks against French civilians) and lying to their Polish allies.  Gamelin told the Poles that half his army was presently engaged with the Germans and that the offensive had caused Berlin to move at least six division away out of the east.  Neither were true.  Rather, the French prioritized moving French civilians away from the border and consolidating their mobilizing army.  The choice to stop enraged mid and lower level officers and gutted what there was of French morale.  Many French troops and civilians had chanted “il faut en finir” (“enough is enough” or “we must put an end”) as the French army mobilized, eager to finish off Hitler’s saber-rattling and expansionist drive.  Now they were being told they couldn’t attack Nazi Germany for fear of a potential future counteroffensive.

By September 21st, the French High Command was no longer willing to indulge the fantasy that they were going to conduct a major offensive and began to retreat back to their side of the border.  By then, the Soviet Union had invaded Poland and it was clear that the country’s fate had been sealed.  Gamelin ordered the French back behind the Maginot Line, managing to easily repel a few German counterattacks that tried to push the French out of their gains early.  As mid-October of 1939 arrived, the French were back from where they started, having suffered 2,000 casualties while only inflicting roughly 700 casualties and 11 lost planes on the Germans.  For the time being, the active war had ended – the “Phoney War” in the West had begun.

French soldiers play cards waiting awaiting orders

The Saar Offensive remains one of the great “What If’s” of the Second World War.  In the aftermath of the war, the scale of the Allies’ missed opportunity became clear.  The Germans would admit that in September of 1939 the Siegfried Line was constructed more out of propaganda than cement, with Field Marshal Gerd von Rundstedt literally laughing out loud at the lack of progress when given a tour of the line.  German Chief of Staff Alfred Jodl declared at Nuremberg that the only reason Germany didn’t “collapse” in 1939 was due to the Allied inactivity at the start of the Polish campaign.  General Siegfried Westphal, Rommel’s future chief of staff, defined the failure in even greater detail, stating that if the French had attacked in full force in September of 1939 the German army “could only have held out for one or two weeks.” 

While there’s little doubt that the Saar Offensive failed in large part due to Allied passivity, particularly with Maurice Gamelin and the French High Command, the odds of Allied success were perhaps not as clear cut as revisionists, then and now, believe.

As stated earlier, neither the French nor the British were prepared for a major conflict or even fully mobilized.  The combined Franco-British forces held fewer than 1,000 combat-capable aircraft and the French held 765 armored vehicles of all types.  These numbers would still dramatically increase over the following months, but hardly constituted a fighting force that could withstand significant early losses and still maintain the core Allied strategy of meeting an German flanking maneuver and keep the war away from France’s industrial strength and population centers.  The broken logistics of the French army alone likely would have endangered an attempted sustained offensive deep into Germany and unless the Allies could reach the Rhine, there wasn’t a natural or man-made defensive barrier they could reinforce to allow the rest of the army to catch up and await a German counterattack.  Indeed, a careless Saar Offensive might have risked the early Allied armies the moment the Germans turned west.

The eventual end game – Hitler tours a fallen Paris in 1940

The true failure of the Saar Offensive was a failure among the Allies to fully acknowledge they were once again engaged in a world war.  Having spent the prior twenty years trying to avoid the calamity of another conflict, the French and British refused to take decisive action even once at war.  The French Air Force and British RAF may not have known how few fighters were arranged against them at first, but they would have found out had they started bombing German factories and railways as some in the Allied command wanted.  The Allies might not have been able to hold any gains in the Saarland, but they could have conducted essentially a large-scale raiding party, destroying German infrastructure and discovering what a paper tiger the Siegfried Line was in actuality.  Neither action would have likely saved Poland nor necessarily caused Berlin to sue for an immediate peace, but they would have demonstrated to the Germans – and the Allies’ own populaces – that London and Paris were committed to do what it took to end the peril of Nazism.