Fritz Fischer was a German historian who focused on WWI. Many German historians had argued that Germany only had limited responsibility for WWI but Fischer found a significant amount of evidence to the contrary. When Fischer published his work he was attacked by other German historians.
A more in-depth look at the controversy: https://www.historians.org/publications-and-directories/perspectives-on-history/march-2000/in-memoriam-fritz-fischer
In this RLE the “direct experience” could be looked at a few different ways. One is through the way German historians took positions on WWI responsibility based more on their “direct experience” as Germans rather than on the historical record. The other way to look at “direct experience” in this RLE is by looking at Fritz Fischer himself and his work. Of course, even though he was responsible for significant breakthroughs in historical understanding his work still had to go through the academic process of peer review.