Army of the Duchy of Warsaw Army of the Duchy of Warsaw refers to the military forces of the Duchy of Warsaw . The Army was significantly based on the Polish Legions ; it numbered about 30 , 000 and was expanded during wartime to almost 100 , 000 . It was composed infantry , with a strong cavalry force , supported by artillery . The Napoleonic customs and traditions resulted in some social tensions , but are generally credited with helpful modernization and useful reforms . Size . The cadre of the Army of the Duchy of Warsaw was formed by the legionnaires of the Polish Legions . In addition , it was filled by older soldiers from the Army of the Polish - Lithuanian Commonwealth , who responded to the call to arms of Józef Poniatowski , and patriotic youth . In 1808 , after the first emergency period was over , and the Duchy felt more secure , those who wished to leave the army were given leave . The army was expanded with large waves of new recruits on the eve of new wars in 1809 and 1812 , when the Duchy fought other partitioners , which resulted in influx of recruits from those territories , hoping to see their home liberated . The final recruitment phase was that in the fall and winter of 1813 , when the Duchy was trying to rally to its own defense in the aftermath of the Napoleon ' s defeat in Russia . Upon its creation , the Army numbered 30 , 000 ( out of the Duchy ' s population of 2 . 6m ) . The size of the army was of a considerable economic burden to the small state . The army was expanded several times ; it was doubled in 1809 . Several regiments were sponsored by the French . For the war of 1812 , almost 100 , 000 men were fielded - more than the Army of the Polish - Lithuanian Commonwealth ever numbered . In the fall of 1813 , the Army , reconstructed after the defeat in Russia , numbered about 20 , 000 or 40 , 000 ( sources vary ) . It is estimated that about 180 , 000 to 200 , 000 men served in the Army throughout its brief existence . In addition to the Army of the Duchy of Warsaw , Poles also served in other formations allied to France ; most notably , the Vistula Legion . In addition to the standing army , a national guard could be called into action , as has happened in 1809 and 1811 . Notable Polish commanders of the Army of the Duchy of Warsaw included prince Józef Poniatowski ( who was the army chief commander throughout most of its history ) and Jan Henryk Dąbrowski . Composition . The Army of the Duchy of Warsaw was composed of the following formations : In 1813 several units of light cavalry , the Krakusi ( Cracus , or Polish cossacks ) , were planned ; in the end , one regiment was formed . Culture , training and time of service . The Army was a site of cultural clash of new , democratic French traditions and old Polish customs , with clashes on the role of nobility in the military - with some conservatives attempting to restrict the officer rank to the nobles . The French revolutionary and civic traditions , passed through veteran legionnaires , resulted in higher more and motivation of the peasant recruits , compared to the army of the old Commonwealth . The educational role of the army is seen as one of its major if unintended successes . The army was also improved due to the modernization and adoption of modern French military rules and tactics . Overall , the era of the Duchy of Warsaw marked a period of modernization of the Polish Army , with a new military doctrine and science that was codified by Polish military scholar of that era , Ignacy Prądzyński . The obligatory time of service was set at 6 years , with any citizens aged 21 to 28 having a chance to be randomly chosen for conscription . The Army was supported by the new schools , with the 3 - year Elementary School and a 1 - year Applicant School for Artillery and Engineering . Overall , the Polish units were reconned by the French to be highly motivated and of high quality . Operational history . The army was formed at the time of the creation of the Duchy of Warsaw in 1807 . The army participated in numerous wars on the side of Napoleonic France , including in the War of the Fourth Coalition ( 1806 - 1807 ) , Peninsular War , the War of the Fifth Coalition ( primarily in the Polish - Austrian War ) of 1809 , and in the War of the Sixth Coalition ( in particular , in the French invasion of Russia ) of 1812 - 1813 . In the Russian campaign of 1812 , the Polish units formed an entire corps ( the V Corps ) of the Grande Armée . The army sustained over 70 % losses . The Army suffered further heavy casualties in the battle of Leipzig in 1813 , where Prince Poniatowski died . After Napoleonic defeats in 1813 , the Duchy was occupied by Napoleon ' s enemies . As several garrisons in fortresses held out , much of the Army followed Napoleon back to France that year . Disorganized after Poniatowski ' s death , in 1814 , the army still had about 8 , 000 people in French - controlled territories , mostly in France , but was incorporated into French Army , and ceased to exist after the final defeat of Napoleon . After the Treaty of Fontainebleau most of the Polish soldiers were given into the custody of the Russians .