Of, or pertaining to, the ancient civilisations of Europe, in particular the pre-christian Greek and Roman civilisations. The humanists were particularly fond of finding and translating ancient Greek texts to add to their knowledge.
An Ancient is a military rank, often seen in the 16th century armies of especially England. Probably somewhere approximately equivalent to a lieutenant in the modern era. At the very least it ranked underneath a captain, who was a knight as often as not.
The term was eventually replaced by ensign in the middle of the 17th century by most countries (Ireland being a notable excepetion) and as in earlier times referred to one who would bear the standard of the unit, company or army in which he was associated.