i looked into it, the negroes at that time were rhineland basdummys, black french fathers and white german mothers, this happened because of WW1 and france's colonial recruitment for the war. Claus created "Sonderkommission 3" which was a commission to locate and forcibly sterilize children, there were 385 cases of sterilization overall. Claus often stated in his book about black people and didnt quite like him, and still persecuted them in germany, but not as hard as jews. i recommend to look into this more