Blutgruppe tattoo on the arm of an SS Officer. Blood Type A.
The SS blood group tattoo was applied, in theory, to all Waffen-SS (W-SS) members (except members of the British Free Corps). It was a small black ink tattoo located on the underside of the left arm, usually near the armpit. It generally measured around 7mm (0.28 inches) long, and was placed roughly 20cm (8 inches) above the elbow.
The idea behind the tattoo was that if a soldier needed a blood transfusion and he was unconscious, or his Erkennungsmarke (dog tag) or Soldbuch (pay book) were missing, the doctor could still ascertain the soldier’s blood type by locating the tattoo. The tattoo was generally applied by the unit’s Sanitäter (medic) in basic training, but could have been applied by anyone assigned to do it at any time during his term of service.
When the war ended, the Allies were keen to catch all W-SS members on account of the high volume of war crimes committed by some units. The blood group tattoo helped greatly in identifying former members, leading to the prosecution of guilty men, and in some cases the execution of W-SS men, regardless of whether or not they were actually guilty of war crimes. Many W-SS men tried to remove the tattoo, some by burning it off with a cigarette, but the scar left behind was almost as incriminating, leading some to make a similar scar on the opposite side of the their arm and then claiming the scars were from a bullet which had passed through their arm. In these cases, the Allies would often X-ray the arm to see if any bone damage had occurred, as would have had a bullet actually passed through the arm at those points.
Some members of the SS (such as Josef Mengele and Alois Brunner) evaded capture in part because they did not have the blood group tattoo included.
According to Reche (based on his studies of the rural inhabitants of northwest Germany), the long-headed European races were originally characterized by blood type A. Another, less well defined race with origins somewhere in Asia was characterized by blood type B, whereas the pure-blooded inhabitants of pre-Columbian America had neither type A nor B but were exclusively of type O. Reche concluded that a strong correlation had once existed between race and blood type, and that subsequently, through racial intermarriage, the races had become intermingled.
-Racial Hygeine, Robert Proctor