The little-known history of the counterintelligence department of the 12th Army headquarters is examined through the prism of the activities of two tools for countering espionage – the spy squad and secret employees. Based on unfamiliar archival documents introduced into scientific circulation (counterintelligence correspondence with gendarmerie departments, orders for the 12th Army, information on persons suspected of military espionage, reports on the detention of spies, lists of agents, etc.), a conclusion is made about unsatisfactory results of the work of army counterintelligence. Observant agents and secret employees showed their professional unsuitability in the fight against enemy agents. There was not enough legal and special knowledge and practical experience. In rare cases, the detention of a state criminal (German/Austrian agent ortraitortothe Motherland) ended with an inquiry or investigation,followed by legal proceedings. The skillful leadership principle – the organization of tactics and the strategy for identifying the military-criminal element – is also not visible. The bulk of the spies were detained by chance and, as a rule, on the front line of defense of the Russian army, thanks to the vigilance and observation of itsmilitary personnel.