1915 he was chief physician of the 7th Regiment of Infantry. On 10 May 1915 he was promoted to the rank of captain doctor and his medical services covered all of the Polish Legions. In July 1916, he distinguished himself during the Battle of Kostiuchnówka. From 1 October 1916, after the dissolution of the 7th Regiment of Infantry, Składkowski became chief physician of the 5th Infantry Unit. On 16 July 1917, during the Oath crisis, Składkowski, who officially was considered a Russian subject, was released from the service in the Legions. On 22 July 1917 he was interned in Beniaminów, and remained there until 2 August 1918. After his release, Składkowski worked as a physician at Saturn Coal Mine in the city of Czeladź. Polish Army In November 1918, Składkowski, wearing his Legions uniform, disarmed German soldiers in the region of Zagłębie Dąbrowskie. Being a captain, he took over command of the newly created Polish Army in the area, and briefly commanded the Military District of Zagłębie Dąbrowskie. On 3 February 1919, Składkowski was named chief of staff of Colonel Rudolf Tarnawski, commandant of Będzin Military District. Promoted to major, he became chief medical officer of the newly formed 2nd Legions Infantry Division. With this unit, he fought in the Polish–Soviet War, capturing Minsk in August 1919. In the autumn of 1919, Składkowski was named chief medical officer of the Operational Group of General Lucjan Żeligowski. On 7 February 1920, he was appointed to the post of manager of the organizational section of the Ministry of Military Affairs' Medical Department. Promoted to colonel, in August 1920 he was a government envoy to the Polish Red Cross. In January 1921, Składowski was named inspector of medical units of the Polish Army. He then left for France, for a course at the École spéciale militaire de Saint-Cyr. In November 1924, he was one of the officers who resigned from active service in the so-called strike of the generals; the joint resignation of the officers was, however, rejected. On 1 December 1924, Składkowski was promoted to brigadier general. While in France, he met and fell in love with a Frenchwoman, Germaine Susanne Coillot. In 1925, he converted to Calvinism in order to get a divorce from his first wife, Jadwiga Szoll. In January 1926, he married his French love, who changed her last name into Coillot-Składkowska. During the May Coup, Składkowski supported Józef