Introduction and objective: This research paper was created as part of the project “Polish Campaign of 1939 – Synthesis” conducted by the War Studies University. The aim of this three-part article is to provide a comprehensive account of the role of the Polish health service during the 1939 campaign. The subsequent sections examine the initial capabilities of the health service, wartime planning and preparations, and the actual participation of medical services during the campaign. The primary research question focuses on the factors that led to the collapse of Poland’s medical services in September 1939. Material and methods: The author drew on historical materials collected at the Central Military Archive (Warsaw-Rembertów) and the Archives of the Polish Institute and the General Władysław Sikorski Museum (London). This synthesis also incorporates previous research by historians, published sources, and a wide range of personal recollections and testimonies. Results: The Polish health service suffered a defeat in 1939. The system for evacuating and treating the wounded collapsed within the first days of the war. Evacuation difficulties, rapidly depleting stocks of prophylactic serums, and delays in surgical care led to widespread complications from infected wounds, including numerous cases of tetanus. Conclusions: The main factors that led to the medical crisis in 1939 included the very limited initial capacity of the medical service (staff shortages, underdeveloped hospitals), low financial investment and insufficient material reserves, the highly centralized medical supply system, reliance on railways for medical evacuation, the low degree of motorization in both the Polish Army and society, poor road conditions, and the nature of the enemy’s operations – sudden, deep attacks on the rear, disruption of communication networks, and targeting of civilian areas.