Aleppo. Mosul. Fallujah. Tikrit. These are the names of cities in Iraq and Syria where wars have raged over the past two years, featuring human cruelty on a scale that most people can’t fathom. Islamic State in particular, though not exclusively, has perpetrated some of the most heinous acts of barbarism on men, women and even children seen in our lifetimes. It’s easy sometimes for us in the West to shake our head and wonder how those Muslim radicals could be so vicious. But as was vividly reinforced to me earlier today, it isn’t simply “those people” in the Middle East that can be so murderous.

The potential to act this way resides, usually dormant, in the hearts of all men. However much we wish it weren’t so, we in America are not immune from this danger.

As I write this, I am in a car driving through south-central Poland on my way back to Lodz, where I have been participating in a NATO conference. I spent the first half of the day in a small town near the southern border of Poland called Oswiecim. You probably know it better by its German rendering: Auschwitz.

I have previously visited the Holocaust Museum in Washington, DC, and the concentration camp at Dachau, near Munich, and remembered how horribly the Jews and others had been treated. I even had a general understanding that Auschwitz was really bad. Until I visited the twin camps of Auschwitz and Birkenau, however, I had no idea the intensity of the inhumanity that was inflicted there on the Jews, Poles, Soviet prisoners of war and others from all over Europe.

Auschwitz wasn’t a concentration camp as much as a death camp. According to camp records, upwards of 1.1 million people were slaughtered in this one camp system alone. It was the primary place where the Nazis sent Jews from territories they had conquered from all over Europe to effect Hitler’s “final solution” to destroy the Jewish race. They were not sent there primarily to do hard labor. They were sent there to be murdered. There were many horrific, insufferable things done to Jews at Auschwitz, but to me one stood out in its stunning cruelty.

At the camp train station, the freight cars that were stuffed with Jews would stop at a large platform. Once the doors were open, all the men, women and children were ordered out and separated into two columns—men and older boys in one line, and all the women and children in a second. A German doctor would then make a quick examination of the men, separating them into a further two groups. All children and mothers were told they had to get deloused and shower before being assigned their living space in the camp, and were escorted to a cleaning facility.

Once there, the women were shaved to the scalp and all their hair collected (it was later sent back to Germany in bulk to be used as raw materials for textiles). They were then directed to remove all their clothes and place them neatly on hooks. My tour guide explained that the guards would tell the women, “‘Remember the number over the hook, so you can quickly get dressed after the shower,’ so the women would believe everything was normal and they could be controlled.” But after entering the “shower room,” the doors were sealed behind them, and Zyklon B gas dropped in holes in the ceiling. The gas was lethal but often not fast-acting.

Survivors described hearing shrieks of agonizing screams from the women and children in the chamber for what seemed like an eternity. About thirty minutes after the last of the screams died off, other Jewish prisoners would then be forced to go pick up the dead bodies and move them into the next chamber, the crematoriums, to be incinerated.

Meanwhile back at the train station, the men were divided into two additional groups. Along with a handful of strong, healthy women, those deemed capable of doing hard work were sent one way, and all the old men, boys and those deemed to be sick or weak, another. The second group of men suffered an identical fate as the mothers and children. That is staggering to consider.

There was no intent even to use them per se as slave labor. A few were kept alive only to provide the labor to facilitate the deaths of their fellow Jews, often including their own family and friends. Mothers and children were given not the slightest consideration of mercy. They were just slaughtered like animals. It is estimated that between 70 and 80 percent of all people who arrived on a given train were put to death immediately.

At the height of operations at Auschwitz, upwards of five thousand men, women, boys, girls and elderly were painfully murdered each day and then had their bodies turned to dust, wiping out even their memory from the earth. Today in the Middle East, media reports often contain graphic descriptions of the heinous acts ISIS commits against their prisoners, frequently including women and children. We are tempted to think those radicals in the Middle East are a special breed of subhumans. They are not. There is no race, sex, or ethnicity on earth that is exempt from the capacity to commit atrocities just as heinous.

Over the past twenty years, I have had the opportunity to visit the sites of some famous battles and other locations where huge numbers of men and women were slaughtered: Stalingrad in Russia (over a million killed), the World War I slaughter at Verdun (an estimated half a million killed), the Battle of Pusan Perimeter in Korea (total casualties of over one hundred thousand), the World War II battle at Bastogne (approximately seventy-five thousand killed) and the American Civil War battlefield at Gettysburg (fifty thousand casualties).

Moreover, the world has suffered such murderous tyrants such as Pol Pot in Cambodia (where nearly two million were killed); the Japanese slaughter of Chinese in Nanking during World War II (an estimated three hundred thousand were slaughtered); Mao, who condemned an impossible-to-believe forty-five million of his own countrymen to death; and Stalin, who was responsible for an astounding forty million Russians.

I saw more than my share of death and destruction of war over a twenty-one-year military career, and have always been strongly motivated to do all in my power to protect and defend the citizens of my country from ever being victimized by such barbaric men. That desire is just as strong today. But I think we must periodically remind ourselves that to protect our own population we must avoid, at all costs, getting into situations where that dormant evil spark that lies deeply buried in virtually every human heart, is never kindled among our citizens.

The thing that struck me most during my visit at Auschwitz was what the tour guide said just before the end of the tour. It seemed like she looked right at me and said that, as we surveyed the barbarity of the Nazi regime, we had to “remember that prior to the Second World War the Germans were the most civilized country in Europe.” May we be ever-conscious of our own hearts and ever-vigilant to keep those sparks doused.

Daniel L. Davis is a retired U.S. Army colonel who served multiple tours in Afghanistan. He is a senior fellow with Defense Priorities. Follow him on Twitter @DanielLDavis1.

Image: From the museum at Auschwitz. By Daniel L. Davis.