In his book, "Mission at Nuremberg," author Tim Townsend tells the fascinating story of Army chaplains Henry Gerecke and Sixtus O'Connor, who ministered to the Nazis on trial at Nuremberg, Germany, in the aftermath of WWII in 1945-1946. This largely untold story takes the reader into the cells of the accused and the courtroom where their crimes against humanity were prosecuted. The twenty-one Nazis -- all senior leaders under Adolf Hitler --were both recognized and reviled for their role in orchestrating the most systematic genocide in human history, and included such men as Hermann Goering, Albert Speer, Whilhelm Keitel, Hans Frank, and Ernst Kaltenbrunner.

As the trial unfolded and the world awaited their judgment, both Gerecke and O'Connor worked behind the scenes on a far different mission: to bring these men to faith prior to their judgment -- and for some -- their execution.

Towsend, who was named the Religion Reporter of the Year by the Religion Newswriters Association in 2005, 2011, and 2013, currently works as the senior writer and editor at the Pew Research Center's Religion and Public Life Project in Washington, DC. I recently met with him to discuss "Mission at Nuremberg," and gain his insight into its message and meaning.

Why did you decide to write this book?

Townsend: For me, it was always about the story. When I found Henry Gerecke's story, and learned no one had told it yet in full, I wanted to be the one to do so. As a journalist, I'm always looking for stories that allow me to explore larger themes -- in this case, how good confronts radical evil. When you can write about big ideas like that using a compelling, if little known, piece of history as the thread to hang the narrative on, you've found a great story.

What kind of research went into the writing of the book, and what kind of challenges did you encounter?

Townsend: I went to the Hague a couple of times to observe trials at the International Criminal Court (ICC), the legislative descendant of the Nuremberg trials. I also spent some time with the chaplain who ministers to the ICC's defendants. I traveled to Croatia and Serbia with my former theology professor, Miroslav Volf. Volf, who is the pre-eminent theologian on forgiveness and reconciliation issues, grew up in both countries and formed his theology based on that experience. I also spent time in Jerusalem with the Wiesenthal Center's Efraim Zuroff - often called "the last Nazi hunter" - who spoke to me about the differences between forgiveness and justice. I also went to Rwanda and traveled a bit with Stephen Rapp, the U.S. Ambassador for War Crimes who - in a previous assignment - prosecuted the Rwanda genocide persecutors. And I also interviewed prison chaplains there who minister to the genocide perpetrators - some of them, to the men who killed members of the chaplains' own families. (I wrote about that recently for CNN: I spent time at the U.S. National Archives and the U.S. Army Heritage Center at the Army War College. And, of course, I spent time doing research in Nuremberg. The list goes on, but those are some of the highlights.

You interviewed several Army chaplains as well. How did these interviews help you understand the role of Army chaplains -- both then and now?

Townsend: I spent a few days at the Armed Forces Chaplaincy Center in Fort Jackson when I was researching the book. There's a chapter in the book that looks at the history of military chaplaincy, and within that, the dozens -- if not hundreds -- of hats chaplains have worn through the years, from postal officers to band directors to VD (venereal disease) control officers to rifle-range scorers. Knowing the history of the chaplains that came before Nuremberg, and talking to present-day chaplains and chaplains-in-training gave me a better understanding of why Gerecke and O'Connor were asked to take this assignment, and why they agreed to do it.

As you studied his life, what struck you the most about Gerecke's character, ministry and service?

Townsend: Gerecke was a driven man. When he saw someone he felt needed to hear about the Gospel message, he didn't hesitate. He was constantly on the move, constantly trying to reach people on the margins -- people in hospitals, asylums, jails. Some Sundays he led half-a-dozen worship services from sun-up to night-fall. When they were old enough, his sons drove him to each service in order to spend more time with him.

The chaplains at Nuremberg provided religious support to - not only the Nazis on trial - but also to some of their family members, many of whom were destitute. Your story captures the breadth of ministry these chaplains provided to all parties involved in the trial.

Townsend: Yes - seeking out and ministering to, the families of the Nazi prisoners (but also the Nazi trial witnesses imprisoned at the Palace of Justice) was very important to both chaplains. That ministry continued throughout the trial - and in at least one case, after the trial was over.

They also ministered to the dozens of Nazi witnesses (also being held in the Palace of Justice prison), the families of both the defendants and the witnesses and the members of their own unit -- the 6850th Internal Security Detachment. Gerecke also took over a small, bomb-blasted Lutheran church in the village of Mögeldorf on the outskirts of Nuremberg, and ministered to GIs and others in the Nuremberg trial community, but also to German residents of the city who showed up. That sense of dedication to his job impressed me very much.

Gerecke and O'Connor's ministry to the Nazis stirred controversy in religious circles as well as in the general public. What reactions or responses have you received since the release of your book?

Townsend: There have been very few people who have taken issue with the story. For the most part people are reading the book the way I'd hoped. Obviously, the Holocaust is a sensitive topic and a book about two Christian men who ministered to the architects of a genocide that targeted Jewish people is going to provoke conversation. And I think that's what the book has done -- which is a good thing. Anytime people of different faith groups can discuss their theological differences and similarities in a way that's respectful and thoughtful, that's a good thing.

One of my goals was to look at the issues of forgiveness and justice through both Christian and Jewish lenses, to place them next to each other in the context of this particular story -- not to compare them and ask which is "right," but simply to inform readers who weren't familiar with one theology or tradition.

What do you think Gerecke and O'Connor's legacy is from Nuremberg?

Townsend: As I wrote this book I became more and more convinced that I could never have done what they did at Nuremberg. It's interesting to talk about whether each of them may have even gone too far in their ministry to the Nazis. But it's without doubt that both Gerecke and O'Connor offered the thing they each held most dear in their lives -- their faith -- to men who most of the world considered monsters. That's a radical thing to do.

What do you hope that readers get out of "Mission at Nuremberg"?

Townsend: Ultimately, I hope they find a compelling story. As a reader, I love books that simply tell a good story. If someone learns something new about the chaplaincy or World War II or theology, that's great. But my favorite thing to hear after someone has read the book is: "What an incredible story." It's really about honoring these two chaplains by putting part of their lives down on paper and hoping people pick up the book and read about them.