Saar Offensive

According to the Franco-Polish military convention, the French Army was to start preparations for the major offensive three days after mobilization started. The French forces were to effectively gain control over the area between the French border and the Siegfried Line and were to probe the German defenses. The sector was defended by the German 1st Army. On the 15th day of the mobilization (that is on 16 September), the French Army was to start a full-scale assault on Germany. The pre-emptive mobilization was started in France on 26 August and on 1 September, full mobilization was declared.

French mobilization suffered from an inherently out of date system, which greatly affected their ability to swiftly deploy their forces on the field.[4] The French command still believed in the tactics of World War I, which relied heavily on stationary artillery, even though this took time to transport and deploy. Many pieces also had to be retrieved from storage before any advance could be made.[5]

A French soldier outside of a Reichskolonialbund office in Lauterbach

Almost everyone expected a major French attack on the Western Front soon after the start of the war, but Britain and France were cautious as both feared large German air attacks on their cities; they did not know that 90% of German frontline aircraft were in Poland.[6] A French offensive in the Rhine valley began on 7 September, four days after France declared war on Germany. The Wehrmacht was engaged in the attack on Poland and the French enjoyed a decisive numerical advantage along the border with Germany but the French did not take any action that was able to assist the Poles. Eleven French divisions, part of the Second Army Group, advanced along a 32 km (20 mi) line near Saarbrücken, against weak German opposition. The French army advanced to as far as 8 kilometres (5.0 mi) in some areas, and captured about 12 towns and villages unopposed: Gersheim, Medelsheim, Ihn, Niedergailbach, Bliesmengen, Ludweiler, Brenschelbach, Lauterbach, Niedaltdorf, Kleinblittersdorf, Auersmacher, and Sitterswald (occasionally called "Hitlersdorf" in some French reports). Four Renault R35 tanks were destroyed by mines north of Bliesbrück.

By 9 September the French occupied most of the Warndt Forest.[6] On 10 September, while a minor German counterattack retook the village of Apach, French forces reversed the loss only hours later. The French 32nd Infantry Regiment made further gains on 12 September, seizing the German town of Brenschelbach with the loss of one captain, one sergeant, and seven privates.[1] Near the meeting point of the French, German, and Luxembourgeois borders, the Schengen bridge was destroyed.[7]

French soldiers in Lauterbach

The offensive was halted after French forces had occupied the 7 square kilometres (2.7 sq mi) Warndt Forest, which had been heavily mined by the Germans. The French stopped short of the Siegfried line, although they came within a few kilometres south of it, immediately east of Saarbrücken.

The French held German territory along all of the Rhine-Moselle front, but after the collapse of Poland,[6] General Maurice Gamelin on 21 September ordered French units to return to their starting positions on the Maginot Line. Some French generals, such as Henri Giraud, saw the withdrawal as a wasted opportunity and made known their disagreement with it.

As the withdrawal was taking place, on 28 September, a counterattack by the German 18th Infantry Regiment (from the then newly-formed 52nd Division) in the area between Bischmisheim and Ommersheim was repelled by French forces.

On 17 October the withdrawal was complete. There had been about 2,000 French casualties (killed, wounded, or sick).[1]

Louis Faury, head of the French Military Mission to Poland

The Polish Army general plan for defense, Plan West, assumed that the allied offensive on the Western Front would provide a significant relief to the Polish front in the East.[8]

However, the limited and half-hearted Saar Offensive did not result in any diversion of German troops. The 40-division all-out assault never materialised. On 12 September, the Anglo-French Supreme War Council gathered for the first time at Abbeville in France. It was decided that all offensive actions were to be halted immediately. General Maurice Gamelin ordered his troops to stop "not closer than 1 kilometre (0.6 miles)" from the German positions along the Siegfried Line. Poland was not notified of this decision. Instead, Gamelin informed Marshal Edward Rydz-Śmigły that half of his divisions were in contact with the enemy, and that French advances had forced the Wehrmacht to withdraw at least six divisions from Poland.

The following day, the commander of the French Military Mission to Poland, General Louis Faury, informed the Polish chief of staff, General Wacław Stachiewicz, that the planned major offensive on the western front had to be postponed from 17 to 20 September.

From 16 to 17 October, the German army, now reinforced with troops returning from the Polish campaign, conducted a counteroffensive that retook the remainder of the lost territory, still held by French covering forces, which withdrew as planned.[9][10] German reports acknowledged the loss of 196 soldiers, plus 114 missing and 356 wounded.[2] They also claimed that 11 of their aircraft had been shot down as far as 17 October.[3] The French suffered around 2,000 casualties.[1] By then, all French divisions had been ordered to retreat to their barracks along the Maginot Line. The Phoney War had begun.

At the Nuremberg Trials, German military commander Alfred Jodl said that "if we did not collapse already in the year 1939 that was due only to the fact that during the Polish campaign, the approximately 110 French and British divisions in the West were held completely inactive against the 23 German divisions."[11] General Siegfried Westphal stated that if the French had attacked in full force in September 1939 the German army "could only have held out for one or two weeks."[12]