Following the Remilitarization of the Rhineland, Czechoslovak authorities came to the conclusion that any future war would most probably take place by a sudden attack without formal declaration of war. At the time, protection of borders was mostly vested into the authority of the Customs Administration (also called Financial Police), which was controlling the border crossings and collecting customs duties, while Gendarme officers were taking care of general law enforcement mainly within towns. This was deemed insufficient as the Customs Administration could merely enforce the custom duties and general order at border crossings, but not security along the whole border. In 1936, the State Defense Guard was established. Normally, SDG would function only in a very limited way necessary to ensure full readiness of its structure (under authority of Ministry of Interior), with its ranks being filled up with personnel in case of emergency (under military command). Its main task was protecting the Czechoslovak border and it was supposed to be able to immediately close and defend the border for the time that would be necessary for the army to reach the attacked areas in full combat readiness. Initially, the State Defense Guard was composed of selected members of Customs Administration, Gendarme and State Police, but later its ranks were filled also with reliable civilians. In case of any unrest, its squads were further boosted by army soldiers. State Defense Guard included also ethnic-Germans that were deemed loyal to Czechoslovak state (mostly Social Democrats and communists). The State Defense Guard has thus become the main target of the Freikorps' activities.