Artifice.

This is coolbert:

From the Strategy Page CIC # 477 of Professor Al Nofi.

"artifice: noun - Deception or trickery. Something contrived or made up to achieve an end, especially by deceiving; a stratagem or ruse: synonym: wile."

"The Roman Senator Pliny the Younger (AD 61-c. 113) once complimented the Emperor Trajan (r. AD 98-117) by noting 'you can call nearly all your soldiers by name, and know the deeds of bravery of each one . . . .' Trajan is not the only Great Captain said to have displayed this talent. Similar tales are told of other notable commanders, Mithridates VI of Pontus, Caesar, Hadrian, Gonzalvo de Cordoba, Frederick the Great, Napoleon, and more. These men seemingly could spot old soldiers in the ranks and would sometimes exchange pleasantries with them, often mentioning little details of a man’s service or family, thus letting the troops know that their commander knew them personally and worried about their well-being. A powerful gift for a commander, this talent may have involved less talent than artifice."

ADD TO THAT LIST OF THE GREAT CAPTAINS THE NAME OF GENERAL MATT RIDGWAY.

American General as reputed to have known by name [could recognize and recall] no less than 4,000 servicemen he had served with at one time or another. 

As to how this talent among the ancients was  due to "artifice" the reader to the blog will have to read the article for themselves.

coolbert.