I'm trying to translate this into Latin:
"Since that day when Marius the Great defeated the Dragon of Ravenna, its [the Dragon's] spirit has ever protected our family."
Is this correct?
Ab die ipso ubi Marius Magnus Serpentum Ravennae vicerat, eius spiritus familiam nostram semper protexit.
Are there other, perhaps better ways to say "since"? or clearer word orders?