I'm sorry, but there seems to be some confusion in your question. Frederick Flick was a German industrialist who was tried at the Nuremberg Trials, but he was not tried by the American military.
Flick was actually tried by the International Military Tribunal at Nuremberg, which was a joint effort of the Allied powers - the United States, Great Britain, France, and the Soviet Union. The trials were held after World War II to prosecute Nazi war criminals and those who had committed crimes against humanity.
Flick was one of the leading figures in the German industrial complex, and his companies had used forced labor during the war. He was charged with war crimes and crimes against humanity, but was ultimately acquitted of all charges.