When we describe our ordinary historical belief as a belief that Julius Caesar crossed the Rubicon, the words "Julius Caesar" do not have reference but only cross-reference. Proper names may acquire intelligibility either through our being introduced in some way to their bearers, or by being incorporated into a story – "Once upon a time someone lived in Rome who was called "Julius Caesar", and this Julius Caesar conquered Gaul, crossed the Rubicon, and so forth".
We believe that Julius Caesar crossed the Rubicon in the sense that we believe the relevant part of this story; there is no one to whom we are related as believing the whole story of him, but we identify the subject of the later part of the story, ultimately, as simply the "someone" with whom the story begins. ... there is no one of whom I say that he crossed the Rubicon; but I do say that someone crossed the Rubicon, and I have previously said (among much else) that this same someone was called "Julius Caesar".We have a mass of historical documentation concerning Caesar, and a further, even greater mass of documentation about other people of his era, with multiple cross-references between them. We can extend this documentation by writing a biography of Caesar, using the same method of cross-reference, i.e. reference to historical documentation, which makes the name meaningful. Taking all the historical documentation as a whole, including later speculations (including biographies and historical studies) which attempt to remove contradiction or inconsistency, then you have a massive indefinite description of reality. ‘Caesar crossed the Rubicon’ is definite, of course, but only because of this cross-reference.
Is this linguistic idealism? Surely not. For that historical documentation gives us information about the past. Think of cross-reference as a neat way of locating information. (Think of history as a massive set of old-fashioned metal filing cabinets, where you can make ‘singular reference’ to individual sections of a cabinet, and check for cross-references).