Mebbe it's an Anglo-American vs a European continental thingy, but I was always taught (both in Gymnasium grammar school and at the universities I charged up my brain, before I got hit in some ancient teevee play by the predecessor of a light bulb and the brain started leaking), that Caesar's birthday was on the 13th of July. Trust us, darlings, 13 was NOT an unlucky number for the Romans. I think the crux lies in some ancient commentary on a ditto text, that caused a discussion around the date of birth, being either the 12th or the 13th. Mebbe Caesar was born in the middle of the night and because of his rather unusual birth (which seems to have been the cause of a lot of pretty wild stories), some may have forgotten when the golden kid actually popped out of his mommy's tumkin...Oh well. I tend to keep the 13th as Caesar's birthday. Thirteeeeeeeeeeeeeeeeeen!!!!