"Marshall Poniatowski, mounted.

In April of 1811 Poniatowski went to Paris, where he represented the king of Saxony and duke of Warsaw Frederick Augustus I at the baptism ceremonies of Napoleon's son. He stayed there for four months and worked with the Emperor and his generals on plans for the campaign against Russia. Tried to convince the French leaders that the southern route, through the Ukraine, where the climate was warmer, Polish gentry from the Russian partition would join in, and possible Turkish action against Russia could be supported, was the most advantageous theater for the upcoming war. Napoleon rejected the idea, as well as the back-up scenario, according to which Poniatowski would follow such a route alone with the Polish corps, hoping to take over these formerly Polish areas with the expected help from a Polish uprising planned there. For the Moscow expedition Poniatowski became commander of the part of the nearly 100,000 strong Polish forces (the greatest Polish military effort before the 20th century), namely the V Corps of the Grande Armée.

The initial period of the offensive, when Poniatowski was placed under the direction of Jérôme Bonaparte was wasted, but after Napoleon's brother left Poniatowski was briefly put in charge of Grande Armée's right wing. Fighting on the avant-garde on the advance to Moscow he distinguished himself at a number of battles. On August 17 at Smolensk he personally led his corps' assault on the city. On September 7 at Borodino the V Corps was involved in the daylong fight over the Utitza Mound, which was finally taken toward the evening, stormed by the entire corps led by Prince Józef again. On September 14 the Polish soldiers were the first ones to enter the Russian capital; by that time however Poniatowski was convinced that the campaign was not doing well."