On 26 April 1919, the PPSD, the PPS and the PPS Prussian Section united to form a unitary PPS. Daszyński joined its General Council and became one of its chairmen. He also edited its French-language publication "Bulletin Official du Parti Socialiste Polonaise" and the weekly magazine "Trybuna". After the outbreak of the Polish-Soviet War, Daszyński was for concluding peace as fast as possible. He was opposed to the creation of the Council of National Defense, calling it an "abbreviation of the Sejm". However, on 24 July he joined the Government of National Defense ("Rząd Obrony Narodowej") as Deputy Prime Minister (Witos was Prime Minister). He thought that this step (including peasant and socialist leaders) would increase the number of recruits. After victory in the Battle of the Niemen River, Daszyński was more and more in conflict with the rest of the government, especially with the Ministry of Foreign Affairs. He criticized diplomatic staff and Polish policy towards the East, in particular Tadeusz Rozwadowski's plans for an offensive. On 15 December, the PPS General Council asked the Prime Minister to dismiss Daszyński, but he resigned himself on 18 December. The Prime Minister accepted it very unwillingly, delaying till 4 January 1921.