Where did this claim about the Egpytian Theban army come from?

Question

In this old Locomotive Engineers Journal, there is a short discussion of ancient vs modern army sizes. The writer gives a list of very large ancient armies. Most of the items on the list have easy enough sources. For example:

1. Xerxes led 2,641,610 combatants and as many non-combatants. Invasion of Greece, Herodotus.
2. Hamilcar led 2,000 ships and 3,000 smaller vessels, together with 300,000 soldiers. Battle of Himera, Diodorus Siculus. There is a typo here: 2,000 should be 200.
3. Timur had 1,600,000 soldiers against Bayezid, who had 1,400,000. Battle of Ankara, Johann Schiltberger.

However, one of the items on the list I couldn't recognize:

"The city of Thebes had 100 gates and could sent out at each gate 10,000 fighting men and 200 chariots - in all, 1,000,000 men and 20,000 chariots."

This is obviously referring to Egyptian Thebes, but searching for this number only reveals a similar list. In the War Scrap Book of Matilda Gage, a similar list of vast armies in ancient times is contained:

• Some items in the journal's list, like the Battle of Ankara, are omitted.
• Other items, like the Battle of Cannae (80,000 infantry, 6,000 cavalry, Polybius), are only present on Gage's list.
• In both lists, the claim about Thebes is repeated, and is the first item on the list.

Since these are mostly famous battles, it is possible the two lists are totally unrelated. They seem to be organized in loose chronological order, so it seems the claim about Thebes should be in very ancient Egyptian times. But I cannot find where it comes from.

Answer 1

According to Homer, Egyptian Thebes had 100 gates, each capable of issuing 200 horsemen with associated chariots and horses (Iliad, book 9, as translated by Alexander Pope, ca. 1720):

Not all proud Thebes’ unrivall’d walls contain,
The world’s great empress on the Egyptian plain
(That spreads her conquests o’er a thousand states,
And pours her heroes through a hundred gates,
Two hundred horsemen and two hundred cars
From each wide portal issuing to the wars)

According to the Roman geographer Pomponius Mela's De chorographia (book I, chap 9, in a 1585 English translation)

...Thebes, which hath (as is reported in Homer) a hundred Gates, or (as other saye) a hundred Pallaces, the houses of so many Princes, eche of which Pallaces (as the state of affayres required) was wont to send foorth ten thousande armed men.

More recently this exaggeration has been repeated in fiction, where a character says

"It is," said the Doctor of Sorbonne, "because the stock of faith has greatly decreased."

A great deal was said about Thebes and its hundred gates, and of the million of soldiers that issued out of those gates with the twenty thousand chariots of war.

"Shut the book there," said Mr. Andrew. "Since I have taken to reading, I beg to suspect that the same genius that wrote Garagantua, used of yore to write all the histories."

and in nonfiction by the same author

But, who can possibly believe, that through each of the hundred gates of Thebes, there went out two hundred chariots of war, and one hundred thousand combatants ? That would amount to twenty thousand chariots, and one million of soldiers; and, if we reckon one soldier to every five inhabitants, the amount of the population of this single city, would be five millions; in a country which is not so large as Spain or France

(I cannot explain the funny math involved with 100 times 100,000 equaling one million.)