Buchenwald was a Class II concentration camp
for political prisoners, who were mainly Communists. It was not a death camp
where Jews were brought to be systematically killed. Buchenwald was for
hard-core anti-Fascists who were considered more dangerous to the German state
than the political prisoners sent to Dachau or Sachsenhausen, which were both
designated as Class I camps.
General Patton also mentioned that Buchenwald had "a number of allegedly eminent physicians" who were performing "some very abominable experiments on their fellow inmates." The only medical experiment that Patton cited as an example was one in which 800 prisoners in the camp were "inoculated with anti-typhus vaccine and then inoculated with the typhus bug." The vaccine was a failure, and 700 out of the 800 died of typhus.
America had a typhus vaccine and all the American soldiers had been vaccinated before going overseas. According to the March 1945 issue of the Red Cross monthly bulletin, American soldiers held as POWs in German camps were given booster shots of typhus vaccine, which was delivered by the Red Cross and distributed by the Germans. Since this vaccine was only given to Americans, the Germans were working to develop their own vaccine for the rest of the prisoners and for the German Army.
General Patton's observation that the camp was run by the "slaves" was basically correct. When the camp was originally opened, the Nazis brought common criminals from the Sachsenhausen camp near Berlin to run the camp internally. But after the first Commandant, Karl Otto Koch, was relieved of his duties and sent to Majdanek, the new Commandant, Hermann Pister, allowed the Communists to take over. Buchenwald Survivors [No surprise here, see: Typhoid vaccine]