Czesław Fijałkowski was born on 14 April 1892 in Okalewo (now in Rypin County), in the Płock Governorate of Congress Poland, then part of the Russian Empire.

Following the Oath crisis of 1917 he was interned in Beniaminów, but was released in May 1918 and was allowed to join the Polnische Wehrmacht, at the same time secretly cooperating with the Polish Military Organization.

Already in November 1918 he joined the reborn Polish Army in the rank of Kapitan and took part in the defence of Cieszyn Silesia against the Czechoslovak invasion and later in the Polish–Ukrainian War.

In 1930 he was again promoted, this time to the rank of brigadier general, and assigned to the Łomża-based Polish 18th Infantry Division, which he commanded until the end of the interbellum.

Immediately it started a fast march southwards in order to link up with other Polish units fighting in the area of Lublin and Tomaszów Lubelski.