The Border Protection Corps (Polish: Korpus Ochrony Pogranicza, KOP) was a Polish military formation that was created in 1924 to defend the country's eastern borders against armed Soviet incursions and local bandits. Other borders were under the jurisdiction of a separate, regular Border Guard state security agency.
Though the corps was part of the Polish Army, it was commanded directly by the Ministry of Internal Affairs rather than the Ministry of National Defence. It consisted of elite soldiers from all parts of Poland. Initially KOP comprised 6 brigades and 5 regiments, each guarding part of the borders with the Soviet Union. KOP ceased to exist with the fall of Poland in September 1939.
After the Polish-Bolshevik War the Polish eastern frontier was stretched from the border with Latvia to the north, to the Prut river and Romanian border to the south. Although the peace treaty had been signed, the eastern border of Poland was insecure. Armed bands of saboteurs were crossing the border on a daily basis and the weak police forces in the area could not cope with the problem. In 1924 the town of Stołpce located 20 kilometres from the border was seized by Soviet saboteurs and pillaged. Polish Minister of War Affairs, Władysław Sikorski, decided that the regular police could not cope with the problem and suggested that the control of the border be handed over to the Polish Army.
In one of the reports it was stated that the police waits for the army, while the army waits for the police. To prevent such problems in the future it was decided to combine the police with the army. On August 8 the Council of Ministers decided that a special unit, a militarised border police be created for the defence of the eastern frontier. It also granted significant amounts of money for construction of fortified barracks and police stations in the area. Until November of the same year more than 3,5 million PLZ were spent on that purpose. On September 17, 1924, the new formation was officially created under the name of Border Defence Corps.