In September of 1940, Witold Pilecki, a Polish army captain, did the unthinkable—he snuck into Auschwitz. That's right, into Auschwitz. Pilecki knew that something was terribly wrong with the concentration camp and as a committed (Roman Catholic) Christian and a Polish patriot he couldn't sit by and watch. He wanted to get information on the horrors of Auschwitz, but he knew he could only do that from the inside.

So his superiors approved a daring plan. They provided a false identity card with a Jewish name, and then Pilecki allowed the Germans to arrest him during a routine Warsaw street roundup. Pilecki was sent to Auschwitz and assigned inmate number 4859. Pilecki, a husband and father of two, later said, "I bade farewell to everything I had known on this earth." He became just like any other prisoner—despised, beaten, and threatened with death. From inside the camp he wrote, "The game I was now playing at Auschwitz was dangerous …. In fact, I had gone far beyond what people in the real world would consider dangerous."

But beginning in 1941, prisoner number 4859 started working on his dangerous mission. He organized the inmates into resistance units, boosting morale and documenting the war crimes. Pilecki used couriers to smuggle out detailed reports on the atrocities. By 1942, he had also helped organize a secret radio station using scrap parts. The information he supplied from inside the camp provided Western allies with key intelligence information about Auschwitz.

In the spring of 1943, Pilecki joined the camp bakery where he was able to overpower a guard and escape. Once free, he finished his report, estimating that around 2 million souls had been killed at Auschwitz. When the reports reached London, officials thought he was exaggerating. Of course today we know he was right.

Here's how a contemporary Jewish journal summarized Pilecki's life: "Once he set his mind to the good, he never wavered, never stopped. He crossed the great human divide that separates knowing the right thing from doing the right thing." In his report Pilecki said, "There is always a difference between saying you will do something and actually doing it. A long time before, many years before, I had worked on myself in order to be able to fuse the two." The current Polish Ambassador to the U.S. described Pilecki as a "diamond among Poland's heroes."