After the Peace of Riga had been signed, Thommée remained in the army and on 10 August 1921 he was made the commanding officer of the General Army Area Brześć. On 20 October 1922 he became the first officer of the Grodno-based 3rd Military Area Command (DOK III) and at the same time he started his studies at the Higher War School in Warsaw. On 1 July 1923 he was promoted to the rank of brigadier general, and on 15 August 1924 he became the commanding officer of the 15th Infantry Division stationed in Bydgoszcz. One of the most promising staff officers of his times, in 1926 he was sent to Paris, where he graduated from the prestigious Ecole Superieure de Guerre. Upon his return to Poland, he continued his service at various posts, including the command over the Toruń-based 8th Military Area Command (DOK VIII; 1934–1938) and then the Łódź-based 4th Military Area Command (DOK IV).