He has conducted pioneering research into the implementation of the Commissar Order by combat formations of the Wehrmacht and the attitudes of German soldiers based on the surreptitiously recorded conversations of prisoners of war held in Fort Hunt, Virginia, United States.
[2] From 2007 to 2012, Römer worked as a research associate in the project headed by Sönke Neitzel of the History Department at the University of Mainz focused on war perception and collective biography.
This project led to the publication of Soldaten: On Fighting, Killing and Dying: The Secret WWII Transcripts of German POWs by Neitzel and Harald Welzer in 2011.
For this project Römer compiled 100,000 pages of comprehensive documentary material from the interrogation camp at Fort Hunt, Virginia, where about 3,000 German POWs were both interviewed formally and surreptitiously recorded while held there from 1942 to 1945.
Historian Wolfram Wette, reviewing the book, notes that the sporadic objections to the order were merely pragmatic and that its cancellation in 1942 was "not a return to morality, but an opportunistic course correction".
Once again the observation has confirmed itself: the deeper the research penetrates into the military history, the gloomier the picture becomes.Römer's 2012 book Kameraden (published in English as Comrades in 2019) was based on the surreptitiously recorded conversations of German prisoners of war held in Fort Hunt, United States.