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. They were not angry at his methodology but at the fact that his research did not show Germany in a good light.

A more in-depth look at the controversy:

At different points of time different people (including historians) have come to different conclusions on Germany’s responsibility for causing WWI. Even at one particular point in time different researchers have made very different arguments about the extent to which Germany was solely responsible for WWI. Over time and with the work on people like Fischer there has been more of a consensus (ie. more “certainty”).