Which regions/dynasties do the flags in this Fresco about Byzantine-Persian war represent?

Question

Piero Della Francesca painted the following Fresco to depict battle between Heraclius of Byzantine Empire and Khosrou II of Persian Empire.

Which regions or dynasties do the flags represent?

From what I can guess:

1. Black Eagle on Golden field represents the Emperor of Eastern Roman Empire, Heraclius. (As the single headed Roman Eagle remained in use in ERE, albeit rarely. This is attested by presence of Eagle Bearers (Aquilifers/ὀρνιθόβορας) in ERE).

2. Golden lion on Red field probably represents Macedonia. Pictured below, Coat of Arms of Macedonia from 16th century which represents the ancient Lion of Macedonia:

   

   It might also be a flag from Armenia as Armenians also used a lion emblem occasionally. Pictured below, a flag of King of Armenia (German Caption on top reads "Der Konig von der Hindern Armenia" and the image also appears in this 16th century book):

   

3. The Black head with white Bandanna represents Corsica (even though the flag was adopted centuries after the battle or the painting and I am not sure if Corsica was part of ERE back then but it was a part of ERE back then). Pictured below, flag of Corsica:

   

4. The White Cross on Red field seems to be flag of Duchy of Savoy but that can't be right as Savoy was never a part of ERE. Pictured below flag of Savoy:

   

5. The white duck on red green field is harder to guess. Maybe it is a swan? If yes, it could be flag of Malta as Pieta, Malta's coat of arms are a white swan on a black field.

   

So which regions do these flags represent? Or did the artist just made them up in his head?

P.S. Pardon me if I am mistaking between red and green color here.

Answer 1

I can offer a little insight into one of the symbols. The bird in the banner on the left is a goose.
The goose was symbolic to the Romans, dating to a legend concerning geese from a temple of Juno warning the besieged Romans on Capitoline hill of an impending assault on their position during the Battle of Allia, 390 BC. It represents the quality of vigilence, and is mentioned at times as the "Saviour of the Roman Army".This is referenced by the author of books concerning the painter as the "Capitoline Goose":

• Piero Della Francesca: San Francesco, Arezzo, by Marilyn Aronberg Lavin, 1994
• Piero della Francesca, Marilyn Aronberg Lavin, 2002

The goose reappears in similar form as part of the flag of a particular Contrade of Siena, the Oca contrade.

Remember, this work was done as a fresco to record the History of the True Cross, and covers the walls of the Basilica of San Francesco in Arezzo Italy. It was never meant to be a historically accurate reenactment of a battle. It was painted around 1452 concerning the Battle of Neneveh, which took place in 627, so knowledge of the particular elements of the forces under Heraclius would have been limited at best. Other elements of the painting do not accurately represent the history of the battle, the faces of the people surrounding Khosrau II are actually the faces of the benefactors of the church, the Bacci family, and the representation of the beheading of Khosrau II is inaccurate in itself, according to the wiki article on the battle:

Khosrau had already fled to the mountains of Susiana to try to rally support for the defense of Ctesiphon...The Persian army rebelled and overthrew Khosrau II, raising his son Kavadh II, also known as Siroes, in his stead. Khosrau perished in a dungeon after suffering for five days on bare sustenance—he was shot to death slowly with arrows on the fifth day.

So don't try too hard to glean historical information from a painting done 825 years after-the-fact.

Answer 2

1) A black eagle on gold is usually used to represent the ancient Roman Empire in Medieval and Renaissance art — usually a two-headed eagle. Starting in the late 1200s heraldic works claimed that the Holy Roman Emperor used a black two-headed eagle on gold and the Eastern Roman or Byzantine Emperor used a gold two-headed eagle on red. But I have seen other images of Heraclius using a black eagle on gold.

2) Lions were and are very common in coats-of-arms. A gold lion rampant on a red field is the coat-of-arms of Bulgaria today, as well as being attributed to Macedonia. A single gold lion on red, but passant, is attributed to the Duke of Aquitaine. Many other coats-of-arms were attributed to Macedonia and Alexander the Great, not just a gold lion on red.

It is possible that the gold lion on red was the coat of arms of some contemporary Italian lord put in the painting for some reason.

A gold lion on red, or a red lion on gold, was used as the coat of arms of the Kingdom of Lesser Armenia. Heraclius did recruit Armenian allies and attacked Persia through (Greater) Armenia.

3) The black head on white was the coat of arms of Corsica, a region near Italy where an Italian dialect was spoken. But it was a Moor's head, used to represent all kinds of Africans, black people, Arabs, Turks, and Muslims. Thus it might also be used to represent non-Christian Persians. So maybe Piero della Francesca used it as Chosroes's flag. It would be interesting to know the various coats of arms of ancient Persia used in various paintings and illustrations.

3b) What about the blue and gold flag? What was its design and was it supposed to some kind of Persian flag?

4) Yes a white cross on red was the coat of arms and banner of the Count and later Duke of Savoy. But the Count of Savoy might have copied it from his overlord. One flag used by the Holy Roman Empire was allegedly a white cross on red. It is possible that the Emperor's vassals such as the King of Denmark and the Count of Savoy copied it to show their loyalty. And it is also claimed that some Ghibelline cities in Italy used a white cross on red as their coat of arms while many Guelph cities used a red cross on white as their coat-of-arms. Pavia, Novaro, Como, Treviso, and Asti are Ghibeline cities with white crosses on red.

Piero della Francesca was probably familiar with the coats-of-arms of several Italian cities and may have used a red flag with a white cross to symbolize a particular Italian city for some reason. Or maybe to symbolize Christendom — presumably the use of such a flag by the Emperor was to symbolize overlordship of Christendom.

5) To me the "white swan on black" looks like "a pelican in it's piety" a bizzare looking pelican wounding it's breast to feed its young on drops of its blood. The white bird on green looks to me like its legs are a bit too long to be a duck.

I hope my comments are of some use in understanding the problems of identifying the flags correctly.