In the first years of World War I he resided in Switzerland, where he wrote articles for the Polish cause.

In June 1917 he came back to Warsaw and received a job in the administration under the Regency Council.

From 26 November 1917 to 27 February 1918 he was the Minister President of the Polish government.

[2] He resigned, along with the rest of his government after the Treaty of Brest-Litovsk was signed.

[3] In 1940 (World War II) he went into exile in the US, where he published many works for the Polish cause, mainly from an anti-communist and anti-Soviet point of view.