Oberarzt (short: OArzt or OA), literally meaning "senior physician," in English known as first lieutenant (Dr.), was a military commissioned officer rank in the Austro-Hungarian Common Army until 1918, and in the German Reichswehr and Wehrmacht until 1945.
While holders of this rank were commissioned officers, their authority was usually limited to medical matters and medical staff, and they were regarded as non-combatants and accorded the status of "protected persons" under international humanitarian law when participating in humanitarian work during armed conflicts.
As such, they could not be attacked, harmed or taken as prisoners of war, and were entitled under the Geneva Conventions to carry out their work without being inhibited.
In the German Wehrmacht from 1933 until 1945 there were the OF1a-ranks Oberarzt (physician), Oberapotheker (pharacologis), and Oberveterinär (veterinary), comparable to the Oberleutnant/First lieutenant OF2a-rank.
In line to the so-called Reichsbesoldungsordnung (en: Reich's salary order), appendixes to the Salary law of the German Empire (de: Besoldungsgesetz des Deutschen Reiches) of 1927[2] (changes 1937 – 1940), the comparative ranks were as follows: C 8/C 9 The corps colour of the military Health Service Support (HSS) in German armed forces was traditional dark bluedark blue, and of the veterinarian service carmine red.