I want to give you, if I can, an idea of what book research feels like by describing what happened when I went after one particular detail. You can see the sort of back-and-forth reasoning needed to tease out facts from 2,500 years ago.
So, I am writing a mystery set at the Olympics of 460BC, which is the 80th Olympiad. Obviously I want to know who was at the for-real historical event. I start searching, and like any normal human being I begin with Google.
One name hits me at once: King Alexander I of Macedon. Numerous web sites and a popular article from Tufts University all say he competed in the stadion (sprint) event in 460BC. The popular article is by Dr. Evangeline D. Harris Stefanakis, et al. Tufts University, Spring 2004.
(In what follows I'm going to leave off the BC part of the dates, which is common practice when everything is BC. Just remember all the dates are running backwards, so 500 comes before 460.)
Alexander I is not the Alexander the Great (he was Alexander III), but still, this has got to be a good character. It's not every day you can get Macedonian royalty into a story.
I thought I had it nailed and I was feeling so good that when I saw Wikipedia has Alexander at the Olympics of 504 or 500, I made a disparaging remark on twitter about how they got their dates wrong.
Then the highly knowledgable Robert Greaves pointed out, very politely, that Wikipedia is more likely to be correct than the 460 date, because Alexander I began his rule in the 490s, and for once Wikipedia is referencing a respectable book. If so, I can't have him as a character in 460.
I check. The references are A History of Macedonia by Hammond & Griffith, and Thucydides and Pindar: Historical Narrative and the World of Epinikian Poetry by Simon Hornblower. The titles aren't exactly catchy, but these are very respected scholars. Uh oh. But those 500 dates don't look particularly firm either, and what about the sites reporting a 460 date? Robert and I begin discussing what was the likely real date for Alexander. The question has switched from who was there in 460, to when was Alexander at the Olympics? At this point the awesomely knowledgable N.S. Gill joins the hunt. Three people, at least two of whom are really good at researching this sort of thing, were now working their sources. I am enormously lucky to know people like this!
The ensuing conversation was fascinating, fun, and very long, so skipping the blow by blow account, here is what we dredged up between us:
First, the primary sources, which is to say, stuff written at or very close to the time. There are only two documents that refer to Alexander competing at the Olympics: Herodotus and a fragment of a poem from the famous poet Pindar.
The story from Herodotus appears right in the middle of him relating the Persian Wars. This is what he says, from the Penguin edition:
[The Greek nationality of the Macedonian kings] was recognised by the managers of the Olympic Games, on the occasion when Alexander wished to compete and his Greek competitors tried to exclude him on the ground that foreigners were not allowed to take part. Alexander however proved his Argive descent, and so was accepted as a Greek and allowed to enter for the foot-race. He came in equal first.
That's it. No hint of when this happened.
The Pindar fragment doesn't help much either. Most scholars have it dated to some time in the 450s. You would expect Pindar to have written shortly after the event. That explains why some people are giving 460. But The Greek World 479-323 by Simon Hornblower dates Pindar's poem to the 490s, not 450s! If the 490 date is correct then Alexander competing shortly before or after his coronation looks very reasonable.
There is one other document that might help: a chronology written by a guy called Eusebius. Eusebius lived much later but wrote chronologies for all sorts of things, and one of them was a "complete" list of winners of the Olympic stadion event. He was working off source documents now lost to us. Perfect! Robert and I both track down copies of Eusebius.
Guess what? Alexander does not appear on any of them at any date.
Time to give up and open a vein? Maybe not. This doesn't necessarily mean Alex wasn't there, because Herodotus says he came equal first, which means by normal practice there would have been a run-off. Maybe he lost the run-off, in which case he would not have appeared in Eusebius' victor list. We haven't progressed at all.
Britannica has Alexander on the throne by 500. Most other sources give some time in the 490s. Either way, it looks like the 460 date is dead because Alexander would have been way too old. Eusebius does give 44 years as the reign of Alexander. If Eusebius has it right, which he probably does, then Alex must have died in the 440s. Assuming the coronation date is good, of course. No one's too sure about it either, but it's unlikely to be later than 490 because he was a major player by the time of the Persian Wars, which are coming ten years later.
The dates in Wikipedia also look dodgy now, because Alexander would have been doing this for political reasons. The question of whether Macedonia was Greek was a hot topic then, as it still is today, and by entering for the Olympics Alexander was forcing the issue for the royal family at least. He didn't really need to do this when he was a princeling. Also, politically, it seems hard to believe the Greeks were going to admit a Macedonian at such an early date. Macedonians were considered barbarians.
Another source dates Alexander to the Olympics of 478. Why 478? Because 478 was the first Olympics after the Greeks had beaten off the Persian invasion, and Hellene patriotism was running high. Alexander had been one of the defenders of Greece. If a Macedonian king was going to be accepted as a Hellene then 478 was the first time there was sufficient good will to let him in.
So now we have dates of 504, 500, 478 and 460, and of these, the most popularly quoted is 460, the one mostly likely wrong.
Another factor is, the controversial start date of 776 for the Olympics could be causing the trouble, because the Greeks always used Olympiad numbers, not year numbers. Any evidence based on hard year numbers can conflict with Olympiad numbers, which always begin from the dubious 776. There is even a book about this problem: Discrepencies In Olympiad Dating And Chronological Problems by Shaw. In it is this quote: "The years from the accession of Alexander I to Alexander IV is 167 in Eusebius' Chronicle but 120 in Porphyry's version..." Wonderful...what's a 47 year difference between friends? This is the sort of thing that can make you misplace someone by a couple of Olympiads.
Notice the more you check the facts, the more questionable they became. This is a common problem for anyone trying to get precision for that long ago.
Both Robert and N.S. Gill found references to work by Eugene Borza, a highly respected scholar. In In The Shadow Of Olympus, Borza spends a few pages trying to solve the puzzle. He points out, very sensibly, that the whole question hangs on Alexander's age. After considering the pros and cons he comes up with a surprising conclusion: there is no possible combination of age, coronation, politics and Olympiad which works. Borza thinks both Herodotus' story and Pindar's poem are sourced from PR originating with Alexander himself. "They should be discarded both because they are propoganda and because they invite suspicion... Herodotus transmitted some perfectly acceptable historical material concerning the activity of Alexander I during the Persian Wars, but ... his participation at the Olympic Games, and the Hellenic lineage of his family are not among them."
In other words, it never happened.
We now have the options 504, 500, 478, 460, and never.
What's a poor mystery writer to do? Fortunately, I don't need to work out exactly when Alexander was there, I only need to know whether 460 is viable. It probably isn't. I can cross Alexander off my list, unless I really want him as a character and I'm prepared to defend the age problem.
So that's one detail resolved. Total time spent on this was a couple of hours. I estimate there are about 100 details like this in each book. Fortunately they're not all as difficult as this one, but some are.
It might seem like a lot of work for not a lot of reward, but you never know what you're going to find, and sometimes real gems fall out when you least expect, little factoids that turn into major clues.