My results for the request of his OMPF are not typical. Very few World War II Army personnel records we saved from the 1973 fire. That being said, there are still other options when researching Army veterans killed in action during WWII. Ancestry.com has many resources for military casualty listings which include not only service numbers but assigned units. Although it is a fee-based website many libraries offer the site for free. If you have the assigned unit you can trace the unit's movement, as well as that of their higher headquarters, and find a better idea of where your ancestor was when they were killed. I knew that Warren was assigned to the 814th Tank Destroyer Battalion and in a quick Google search of that unit I found many links that gave me an idea of what the unit did during the war. By narrowing the search to Google Books I found books that discussed the history of the unit that I could view and download in some instances. I also visited WorldCat.org, a website that compiles the holdings of libraries from across the country, and found many other books that I could request through interlibrary loan. Many Army divisions also have associations where past members gather and maintain the history of the division. You are especially lucky if your ancestor's unit still exists, as you can find information on their heritage by contacting the Army historian for the unit or its higher headquarters.
For a better understanding of what your military ancestor experienced you can visit The National World War II Museum in New Orleans or visit the website for the U.S. Army Center of Military History which has a myriad of publications and links.
I am especially proud of my uncle and his sacrifice. The search for his service history has been fascinating and only makes me the more proud.