Saar Offensive The Saar Offensive was a French ground operation into Saarland on the German 1st Army defence sector in the very earlier stages of World War II , from 7 to 16 September 1939 . The purpose of the attack was to assist Poland , which was then under attack . The all - out assault was to have been carried out by roughly 40 divisions , including one armored division , three mechanised divisions , 78 artillery regiments and 40 tank battalions . The offensive was stopped and the French forces eventually withdrew amid a German counter - offensive on 17 October . Objective of the offensive . According to the Franco - Polish military convention , the French Army was to start preparations for the major offensive three days after mobilisation 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 . 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 preemptive mobilization was started in France on 26 August and on full mobilization was declared . French mobilization suffered from an inherently out of date system . The French military ′ s ordnance lacked the tank s and airplanes of the mechanized German military which greatly affected their ability to swiftly deploy their forces on the field . 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 ) . French operations . A French offensive in the Rhine valley began on 7 September , four days after France declared war on Germany . Then , the " Wehrmacht " was occupied in the attack on Poland , and the French soldiers enjoyed a decisive numerical advantage along the border with Germany . However , 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 line near Saarbrücken against weak German opposition . The French army advanced to a depth of and captured at least 12 villages and towns , evacuated by the German army , with little resistance . Four Renault R35 tanks were destroyed by mines north of Bliesbrück . On 10 September there was a small German counter - attack on the village of Apach , which was retaken by French forces some hours later . On 12 September the 32nd Infantry Regiment seized the German town of Brenschelbach with the loss of one Captain , one Sergeant and seven privates . The half - hearted offensive was halted after France occupied the Warndt Forest , of heavily - mined German territory . The French army didn ' t reach the Siegfried line . Aftermath . The attack 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 " from the German positions along the Siegfried Line . Poland was not notified of this decision . Instead , Gamelin informed Marshal Edward Rydz - Śmigły that 1 / 2 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 counter - offensive that retook the remainder of the lost territory , still held by French covering forces , which withdrew as planned . German reports acknowledge the loss of 196 soldiers , plus 114 missing and 356 wounded . They also claim that 11 of their aircraft had been shot down as far as 17 October . The French suffered around 2 , 000 casualties between dead , wounded , and sick . By that time , all French divisions had been ordered to retreat to their barracks along the Maginot Line . The Phoney War had begun .