This particular brand of double-dating presented itself in my family history software when it refused to accept a date of 15 Feb 1733. The software kept insisting the date should be 15 Feb 1732/33.

Wuzzup wit dat? I deleted 32/33, tried again. Same result. I tried all fourteen different ways to delete and correct a date, to no avail.

When all else failed, ‘cuz that’s the way I do things ’round here, I decided to try the Help files. (Props to you if you already know the answer here, it took me a good long while to figure it out.) Seems there’s a difference of opinion between the Julian and Gregorian calendars.

Julius Caesar, after consulting with his chief astronomer, came up with a pretty durn good calendar in 46 B.C. It had 365 days and added a leap day every four years. Problem was, it was off… by just a few minutes. By the time Pope Gregory XIII (Thirteen, to his friends) noticed in 1582, the Julian calendar was off by several days.

So the Pope set things straight in 1582, but true to form, it took the Britain and American colonies until 1752 to get up to speed. By then, the Julian calendar was off by eleven days. Further complicating matters, the Julian calendar started on March 25th, not New Year’s Day.

So, here’s where it gets nasty. A good many countries adopted the Gregorian calendar right away. And as British and American record keepers began to feel more and more self-conscious about their old calendar, some of them started converting to the new Gregorian calendar before it was mandated. That’s problem number one.

Problem number two, is that anything that happened, for example, in January, February, or the first 25 days of March of 1733 on the old calendar actually happened in 1732 on the new one. Thus the reason my family history software insisted on double-dating my ancestor. This kind of double-dating went on for nearly two centuries.

And you thought Y2K was a pain?