The scale and methods of the Nazi genocide of Jewish people make it a politically unique event that deserves a special day of memorial.
My favourite book of the last year was Suite Française by Irene Nemirovsky. The two sections in the book were originally planned as the first of six interconnected stories based around the fall of France in 1940 during the Second World War and its consequences.
Nemirovsky never finished them - a French Jew, she was arrested, deported and died in Auschwitz. The books were only recently discovered and published to great and justified critical acclaim.