The past isn’t all that bright, as many history buffs will know. In just the last century, more human deaths have occurred through war than in any other century in history.

Still, history holds a lot of learning moments for us, even in its darker moments.

With the invention of photography in 1826 and the subsequent popularization and mobilization of it, those moments could be recorded.

Let’s look through 20 important but disturbing photos. It’ll be strange, sad, but full of lessons and rare moments.