Period suggestions of influence and possible links to Stirner

The origin of the debate surrounding whether or not Nietzsche had read Stirner's work – and if so, whether he had been influenced by him – seems to lie in apparent similarities between the ideas of the two men as expressed in their writing. These similarities were recognized early and led many, for a variety of reasons, to attempt to determine the precise nature of any possible relationship.
Eduard von Hartmann's book The Philosophy of the Unconscious had been attacked by Nietzsche in the second of his Untimely Meditations. In 1891 Hartmann claimed that Nietzsche must have been aware of Stirner because Stirner was treated in the very book by him which Nietzsche subjected to criticism. As mentioned, Hartmann accused Nietzsche of having plagiarized Stirner. Nietzsche is also known to have read Lange's History of Materialism, where Stirner's book The Ego and Its Own is referred to briefly as "the most extreme, that we have knowledge of". Lange goes on to refer to the "ill fame" of Stirner's book. Nietzsche knew these works by Hartmann and Lange very well.
Paul Lauterbach also appears to have played a role in the origin of the association of the two thinkers. Lauterbach was a close friend of Heinrich Köselitz ("Peter Gast," who was for many years a kind of private secretary for Nietzsche). Lauterbach came to know Nietzsche's work through Köselitz, and was among the philosopher's earliest admirers. He also worked hard to revive Stirner. According to one view this was a part of his project to present Nietzsche as "the great successor, developer and creative transformer" of Stirner. He edited and wrote an introduction to the 1893 Reclam Edition of Stirner with this in mind. Discussing the book in a letter to Köselitz, he wrote "My introduction has only that one objective, to protect innocent people against it [Stirner's book] and to mystify and paralyze the malevolent, substantially with the assistance of Nietzsche." This introduction appeared in all Reclam editions of The Ego and Its Own from 1893 to 1924.Bernd A. Laska, "Nietzsches initiale Krise. Die Stirner-Nietzsche-Frage in neuem Licht". In Germanic Notes and Reviews, vol. 33, n. 2, fall/Herbst 2002, pp. 109–133 ( Engl. trans. online); zu Lauterbach vgl. Bernd A. Laska: Ein heimlicher Hit. 150 Jahre Stirners "Einziger". Eine kurze Editionsgeschichte. Nürnberg: LSR-Verlag 1994 (pp. 18–28); Paul Lauterbach, Kurze Einführung zum "Einzigen und sein Eigentum", in Max Stirner, Der Einzige und sein Eigentum. Leipzig, Philipp Reclam Jun. 1893, pp. 3–10, It reads, on p. 8:
"Geben wir schliesslich dem Probleme Stirners ein Echo aus den Werken seines grossen Nachfolgers, des Ausbauers und Umschöpfers der Ich-Lehre — Friedrich Nietzsche."

Franz Overbeck, who was one of Nietzsche's closest friends, went through the records of the Basle university library and was able to confirm what Nietzsche's erstwhile favourite student Adolf Baumgartner had claimed: that once he had borrowed Stirner's book (on the 14th of July 1874), according to Baumgartner "on Nietzsche's warmest recommendations". Albert Levy independently confirmed that Baumgartner made the claim, and that he (Baumgartner) had borrowed the book. Franz Overbeck's wife Ida reported that during the period from 1880 to 1883 Nietzsche lived with the couple at several points, and that he mentioned Stirner directly. She describes a discussion she had with Nietzsche in which he mentioned Klinger and Stirner as follows:
"Ach," he said, "I was very disappointed in Klinger. He was a philistine, I feel no affinity with him; but Stirner, yes, with him!" And a solemn expression passed over his face. While I was watching his features intently, his expression changed again, and he made something like a gesture of dismissal or defense: "Now I've told you, and I did not want to mention it at all. Forget it. They will be talking about plagiarism, but you will not do that, I know."
Resa von Schirnhofer reports that in 1897 she visited Nietzsche's sister in Weimar:
Frau Elisabeth wanted to hear some things about my meetings and conversations with Nietzsche and asked me, among other things, whether he had discussed with me Stirner and his book The Individual and His Property. After a little reflection, I answered that I did not remember him ever having mentioned this name. She seemed very satisfied with this answer and, reformulating the question, she insisted: whether I could state with certainty from memory that he had not named him. I felt like a criminal under interrogation by a prosecuting attorney and said I could only state that this name occurred neither in my notebook, nor in my memory as having been named by Nietzsche. She, however, came back to this question several times and always received the same answer. But this did not answer the key question as to whether Nietzsche knew Stirner, because not mentioning him to me is not the same thing as his not knowing him. But that Frau Elisabeth asked me this question is very explainable, since R. Schellwien and Henri Lichtenberger had, in their studies of Max Stirner, drawn a few parallels with Nietzsche's theories.
Schirnhofer goes on to make specific mention of a public controversy at this time:
Henri Lichtenberger — if I am not mistaken — visited the Nietzsche Archives shortly before I did and the question of whether Nietzsche had known Stirner's book must have been discussed intensely. Lichtenberger's book on Nietzsche, which appeared soon afterwards, states about this:
"It is certain that despite his claims to complete originality he submitted, consciously or not, to the influence of his contemporaries, and that his thinking, once stripped of its paradoxical and aggressive style, is often much less new than it seems on first encounter. Uncompromising individualism, the cult of the self, hostility to the state, protest against the dogma of equality and against the cult of humanity are found stamped almost as strongly as in Nietzsche, in an author quite forgotten, Max Stirner, whose main work The Individual and His Property (1845) is, from this point of view, very interesting to compare with Nietzsche's writings."
However, Ida Overbeck, who knew Nietzsche very well, suggests that the relationship between Nietzsche's work and Stirner's should not be viewed as simple plagiarism. Her view was rather that Nietzsche owed a debt to Stirner for introducing new ideas that were significant to Nietzsche in his own work:
That Nietzsche and Stirner seem to us so diametrically different, and actually are, is obvious! But we are not thereby doing justice to Nietzsche and are not giving him the attention and respect he wishes and may demand. Nietzsche paid innermost attention to Stirner. He neither proceeded from him nor stayed with him. It was the simplest sense of reality that moved my husband to note that Nietzsche had known Stirner. Stirner represents a very specific element in Nietzsche, though a small one if you wish, but for Nietzsche great and significant because of the scantiness of this element which he happened to be pursuing.