For a time, he studied law and medicine at Jagiellonian University, and work as a civil servant in Kraków.

He was a close coworker of Józef Piłsudski, but after the Oath crisis, he left the Legions and rejoined the Austro-Hungarian Army.

[citation needed] Between February and August 1919, Roja commanded the Polish 2nd Legions Infantry Division, fighting for the return of Poland's sovereignty against the Red Army in present-day Belarus (see the Polish–Soviet War).

In July 1920, when the Red Army reached the suburbs of Warsaw, he planned to declare independence of Pomerelia, and sign a separatist peace with the Soviets.

In August 1930, Roja wrote an open letter to Pilsudski, but the document was confiscated by the censorship before its official release.

In 1937, upon an order of General Tadeusz Kasprzycki, Roja was interned at a psychiatric ward of the Kraków's military hospital.