Tolkien's novels nor Peter ... but this was not the first reference to the Wizard. Gandalf visited Minas Tirith when Boromir and Faramir were young. According to Faramir in The Lord of the Rings ...

Tolkien, a veteran of the First World War ... A key one of these moments comes during The Return of The King, when Gandalf consoles a young Hobbit about to have their first experience of war.