The phrase "ancient tactic" is correct and usable in written English.
It can be used to refer to a strategy or method that has been employed for a long time, often in historical contexts or discussions about traditional practices.
Example: "The army employed an ancient tactic of flanking their enemies to gain a strategic advantage in battle."
Alternatives: "time-honored strategy" or "age-old method."
When even big guns failed to breach its defences yet another ancient tactic was employed.
Terrorism is an ancient tactic, and the criminal behavior of organized nonstate actors is precisely the problem posed by piracy.
Decapitating the enemy's leadership is an ancient tactic of warfare, and US intelligence and strike technology has brought it to new heights.
From the very start Carnot demanded that the ancient tactic of line combat be abandoned, advocating instead attack by masses concentrated at decisive points; eventually his views were adopted by the entire Committee.
The ship's length made her relatively unmanoeuvrable, making it harder for her to use her strengthened stem for ramming, an ancient tactic that was coming back into use at the time.
The subtle portrayals of emotion, the strikingly modern psychology, the ancient tactics, the fate-haunted warriors — all that life almost three millenniums old has been reduced to little more than a bureaucracy of death.
Moreover, some of these ancient tactics may still be practical.
Conversely, Roger Ebert of the Chicago Sun-Times gave it a negative review stating, "Thor is a failure as a movie, but a success as marketing, an illustration of the ancient carnival tactic of telling the rubes anything to get them into the tent".
That's an ancient debate tactic called baiting.
The last quarter of the Mozi preserves the texts of these militias, which present detailed information about ancient defense tactics and siege fortifications (for an overview, see Yates, 1980).
It is also the name of an ancient Roman military tactic, in which soldiers protected their infantry square from projectiles by completely enclosing it with their shields.
