Rubuta ci gaba ga wannan sakin layi - A rabi na biyu na 1926, Berek ya yi aiki a cikin Rundunar Sojoji ta 83 a Kobryn. A watan Disamba na 1926 an mayar da shi zuwa 9th Legions Infantry Regiment, kuma a cikin watan Mayu 1929 - Satumba 1931, ya halarci Wyższa Szkoła Wojenna a Warsaw. Bayan kammala karatunsa na jami'in, ya kasance shugaban ma'aikatan na 4th Infantry Division, wanda aka kafa a Toruń (1931 - 1934), kuma a cikin 1934 - 36, ya umurci 1st Rifle Battalion a Chojnice. An ba shi mukamin Laftanar Kanal a ranar 1 ga Janairu, 1935, Berek ya yi aiki a Janar Janar na Poland (Oktoba 1936 - Yuli 1939). Bayan 'yan makonni kafin mamayewar Poland, an tura shi zuwa Jarosław, don ya jagoranci Rundunar Sojoji ta 3. Berek ya kasance a matsayinsa har zuwa mika wuya na Modlin Fortress, a ranar 29 ga Satumba 1939 (duba Yaƙin Modlin
) Ya ce: