The following passage from John Steinbeck in East of Eden, 1952, is a salient reminder of the mutability of memory:
….No one outside the War Department knew the quality and duration of his service. His wooden leg was at once a certificate of proof of his soldiering and a guarantee that he wouldn’t ever have to do it again. Timidly he began to tell Alice about his campaigns, but as his technique grew so did his battles. At the very first he knew he was lying, but it was not long before he was equally sure that every one of his stories was true. Before he had entered the service he had not been much interested in warfare; now he bought every book about war, read every report, subscribed to the New York papers, studied maps. His knowledge of geography had been shaky and his information about the fighting nonexistent; now he became an authority. He knew not only the battles, movements, campaigns, but also the units involved, down to the regiments, their colonels, and where they originated. And from telling he came convinced that he had been there.
(Steinbeck Centennial Edition, Penguin Books, New York, at page 17)