At right is a picture of Jews in line for a train heading to one of the most terrible establishments ever built in the 20th century; a German concentration camp. The most terrible part of this picture is not what their fate entails, but the fact that they are not criminals or protestors or even men, but (in this photo at least) completely innocent women and children. While other wars have came and gone, the only one in the past centuries we associate with the word "genocide" was this conflict. Did people die in WWI? Lots of them. But there were not nearly as many non-soldier deaths as WWII. Even in todays Middle East conflict, we cannot compare the innocent lives lost with that of WWII. Sadly, millions of Jews, Poles, and other factions were killed solely based on their affiliation. If these people were shown weeks after this picture was taken, they would not be clothed, or have apathetic looks on their faces. Most of them would be lucky to be standing or even alive. That is why this picture is provoking, because in this picture they might not even know the hells they are about to endure, but we do.
In short, this picture would be terrible if it was of soldiers being sent to a concentration camp, or of criminals or even people who had opposed the government's advancement at all. But these were children playing and women quietly in their homes given treatment most American prisoners today don't even endure. That is what makes it beyond hatable.