ante diem iii kalendas sextilias
- ludi Victoriae Caesaris (day 11)
- after 101 B.C. — dedication of the Temple to “The Fortune of this Day” (Fortuna Huiusce Diei) and subsequent rites thereafter; presumably this is one of the temples vowed prior to the Battle of Vercellae
- 69 A.D. — destruction of the Temple in Jerusalem (Av 9)
rogueclassicism 
I think the correct form is ‘Sextiles’ not ‘Sextilias’. ‘Sextilius’ is a personal name, while the month is called ‘Sextilis’.
I think you’re right … and I think I’ve repeated that error for years now …
Isn’t the date a. d. iii Kalendas Augustas?
I’m using the pre-Julius Caesar names for the months … it’s a bit less messy