In the immediate aftermath of the February Revolution, the Russian Provisional Government's obvious weakness, its half-hearted declaration of the right of nations to self-determination and Germany's promises of autonomy in occupied Poland stirred up long suppressed nationalist feelings among ethnic Poles living within the Russian Empire since the partitions of Poland. Roughly 700,000 of them were serving in the Russian military by 1917 and they began forming a Polish army to fight for a "united and free Poland" with the assent of the Provisional Government and general Lavr Kornilov of the Russian Army. In August, the newly formed Chief Polish Military Committee, a Polish faction in the revolutionary and split Russian Empire, led by Władysław Raczkiewicz, appointed Dowbor-Muśnicki Commissar of the Petrograd Military District and on August 23 he was appointed commander of the newly formed Polish 1st Corps in Russia, being formed in Russia as part of the Entente forces, serving under the Russian Provisional Government in exchange for its support for some form of Polish autonomy or independence. The reorganization process was complicated by the October Revolution of 1917, which brought Bolsheviks to power, but Dowbor-Muśnicki was able to take advantage of the new government's weakness and general anarchy to form 3 divisions in Belarus by January 1918. At that time the I Corps numbered almost 30,000 men, although the number would fall to 23,500 over the coming months.
Combat
At first, after the fall of the Provisional Government, Dowbor-Muśnicki declared that his corps is neutral towards the Russian factions, and its intent is to join the Entente forces. Soon, however, it became apparent that this was an unreasonable plan, as the Entente forces in the area were weak, and out of two dominant forces — the Central Powers' German Ober-Ost forces, and Russian Bolsheviks - it was the Bolsheviks which were more hostile towards the Polish forces. On, Dowbor-Muśnicki refused an order by the Soviet government to disband the Corps, which quickly led to clashes with the newly formed Red Army and Red Latvian riflemen under Ioakim Vatsetis. After sporadic fighting in late January, on January 31 Dowbor-Muśnicki's Corps had to retreat to Bobruisk and Slutsk, where he was surrounded by German Ober-Ost forces. On February 3, the Corps seized the fortress in Bobruisk. After the temporary breakdown of the Brest-Litovsk peace negotiations on February 10, the Corps also received a status of auxiliary unit from the Germans and joined the German offensive against the Bolsheviks on February 18, taking Minsk. After the signing of the Brest-Litovsk Peace Treaty, which gave all of Poland and Belarus to Germany, Dowbor-Muśnicki's corps remained in Belarus for 3 months, regrouping and performing police duties under German occupation authorities. On May 21, 1918, Dowbor-Muśnicki after acknowledging the Regency Council was forced to sign an agreement with Germans, which no longer considered armed Polish presence in that area useful, that led to the disarmament and effective dissolution of the Corps by July 1918, at which point he and many of his men moved to Poland. The agreement, while criticized by some, nonetheless preserved the core of the Polish military, which proved decisive later that year during the formation of the Polish Army. Soldiers who remained in Russia mostly joined the Polish II Corps in Russia.
