The day of the Normandy landings on June 6, 1944, initiated the Western Allied effort to liberate mainland Europe from the Nazi's.
The Holocaust was the murder of Jews by the Nazi party, this began in 1933 and didn't end until May 8, 1945.
The Nuremberg Trials were judges from the allied powers (Great Britain, France, the Soviet Union and the United States) gathered over the hearings of 22 major Nazi criminals. 12 of the criminals were sentenced to death. This trial took place in Nuremberg, Germany on 1945 and 1946.