Answer
The answer is "His part in the development of blitzkrieg tactics". General Sir Basil Liddell Hart was accused of prompting captured German generals to exaggerate their role in the development of blitzkrieg tactics. This accusation was made by German general Heinz Guderian, who claimed that Hart had pressured him to exaggerate his role in the development of blitzkrieg in order to bolster Hart's own reputation as a military theorist.