My current manuscript is set during the Peninsular War, October 1810-May 1811, from the aftermath of the Battle of Busaco to Fuentes de Onoro, and includes the actions and in some cases the point of view of actual historical figures like Wellington and the French marshals Ney and Massena. (Incidentally, the "n" in "Onoro" should have a tilde, and the "e" in "Massena" an accent mark--anyone know how to add those in Blogger?)
It occurred to me as I researched that I needed to keep careful track of who was where and when. Though the short version of what happened between the two battles looks like a stalemate followed by a retreat, the reality of course was a bit more complicated, and I want to get as close to reality as possible, because that's how I roll.
However, there are also vampires and werewolves in this story, so "close to reality" is a relative term. But having werewolves means you need to know when the moon was full.
What I really needed is one of those big desk blotter calendars, the kind that comes with moon phases and everything, but for 1810-11. Obviously no such product is listed in the Office Depot catalog, so the question I then asked myself was how to go about replicating one, or at least creating an Excel file facsimile thereof.
As always when faced with a new research challenge, I turned first to The Google. I searched on "calendar any year" and started with this, the first link offered. Pay dirt! It even gives the phases of the moon. I punched in 1810, then 1811, and spent half an hour putting the results into an Excel file and formatting it. (I found a site that would generate an Excel calendar for a specified date range, but it was a paid download, and I wasn't going to pay for something I could quickly manage on my own and customize at will should I choose to do so.)
So now I have a lovely calendar for the 8 months of my story. Over the weekend I'm going to sit down and start filling in all the tiny historical incidents that might impact my story, and as I write I'll add what my fictional (and fictionalized historical) characters do in the midst of the real events.
I wonder how long it would've taken me to track down 1810-1811 calendars plus moon phases if I'd been writing this book 30 years ago, as an unusually precocious 9-year-old. :-) I'm not even sure how to go about such a search pre-internet. Get a research librarian to help me track down old farmers' almanacs, maybe? It certainly wouldn't have been the work of half an hour. On the whole, I think I love the internet.