Independent Operational Group Silesia

Independent Operational Group Silesia (Polish: Samodzielna Grupa Operacyjna Śląsk, SGO Śląsk) was an Operational Group of the Polish Army, created in September 1938 to annex Trans-Olza (Zaolzie) from Czechoslovakia.

The Group was commanded by General Władysław Bortnowski and comprised several Army units and five air squadrons.

Altogether, 35,966 Polish officers and soldiers participated in the annexation of Zaolzie.

As a result of the Munich crisis, the Czechoslovak government yielded to Polish pressure and gave up a part of the Cieszyn Silesia region (namely Trans-Olza/Zaolzie) to Poland (as demanded by Poland under a threat of military action).

The Independent Operational Group Silesia was carrying out the annexation from 2 to 11 October 1938.

Silesian Voivode Michał Grażyński , Marshal Edward Rydz-Śmigły , and General Władysław Bortnowski in Czech Cieszyn , 12 October 1938
Ruling that mandates exclusive use of Polish language on the annexed territory issued in Czeski Cieszyn by Leon Malhomme