Why did Constantius Chlorus decide to become a Flavius?

I have been working on this for some time now.my guess is that during the flavian era, they took over the cult of the emperor and propagandized to the entire empire, heavily distributing statues and other propagandistic paraphernalia. When domitian went through his damnatio, the senate worked to undermine what the flavians established, but could not totally undue what was done in the outer reaches of the empire. With the flavians heavily tying themselves into the cult of Jupiter, the other cults, especially Sacerdotes Titiales Flaviales,they established a system that could not easily be erased or undone.

I would futher guess that the legions that were promoted and re-created during the flavian emperors would have had allegiance or at least some sort of deep connection with the flavians.

I wonder if the Neo-Flavian emperors were borne out of what I think went down. I will explore this more. Thought I would throw in my 2 cents.

#educated-guess

https://bmcr.brynmawr.edu/2017/2017.03.56 This article covers a book that describes changes that help spread the deification of the Flavian family.

Article on Flavian propaganda https://www.iwu.edu/history/constructingthepastvol8/vastafinal.pdf

Web page providing details of the 4th legion and its longevity https://www.livius.org/articles/legion/legio-iiii-flavia-felix/

Flavian divi legitimization after jewish wars https://escholarship.org/content/qt9xw0k5kh/qt9xw0k5kh_noSplash_c5a732416863013d5ae47855d4bcf46e.pdf?t=mutljw

It is true that Wikipedia says:

At Milan on March 1, 293, Constantius was formally appointed as Maximian’s Caesar.[17] He adopted the names Flavius Valerius1 and was given command of Gaul, Britannia and possibly Hispania.

https://en.wikipedia.org/wiki/Constantius_Chlorus1

Thus Wikipedia seems to claim that Marcus Constantius changed his name to Marcus Flavius Valeriaus Constantius in 293 and presumably to Marcus Flavius Valerius Constantius Augustus in 305.

According to the notes the information about his promotion to caesar comes from:

Birley, Anthony (2005), The Roman Government in Britain, Oxford University Press, ISBN 978-0-19-925237-4, page 382.

And the information about his name comes from:

Southern, Pat. The Roman Empire from Severus to Constantine, Routledge, 2001 page 147.

there are several possibilities:

1) It is very commonly known (or believed or assumed) that Constantius took the names of Flavius and Valerius when appointed Caesar in 293, and thus the Wikipedia contributor didn't see the need to give a specific footnote for Constantius adopting the name Flavius.

2) A statement that Constantius took the names of Flavius and Valerius when appointed Caesar in 293 is in one or both of the two sources cited for that paragraph of the Wikipedia article. Thus the source(s) should give their sources.

3) It is not commonly known (or believed or assumed) that Constantius took the names of Flavius and Valerius when appointed Caesar in 293, and so the Wikipedia contibutor should have seen the need to give a specific footnote for Constantius adopting the name Flavius, but didn't, and it is not in either of the two sources given.

DIR De Imperatoribus Romanus does not discuss Constantius's name.

http://www.roman-emperors.org/chlorus.htm2

One logical place to look would be Jones, A.H.M., Martindale, J.R. The Prosopography of the Later Roman Empire, Vol. I: AD260-395, Cambridge University Press, 1971

One clue is the name of his first wife Flavia Iulia Helena Augusta. He divorced her sometime before 389 to marry Theodora, daughter of Emperor Maximian. She was appointed Augusta by her son Constantine in 325.

https://en.wikipedia.org/wiki/Helena_(empress)3

So when did she get the name Flavia? Was she born Flavia Julia Helena about 248 or 250? Did she became Flavia when she married Constantius about 270? Did she become Flavia only after her son constantine was proclaimed emperor in 306?

Turns out that wiki is misleading on this point (I will try to amend it).

The original name was Flavius Constantius. My reference for this is p. 139 of the following paper.

Salway, Benet. "What's in a Name? A Survey of Roman Onomastic Practice from c. 700 BC to AD 700." Journal of Roman Studies 84 (1994): 124-145.

When in 293 the imperial college was doubled by the recruitment of two Caesars, each to be lieutenant and designated heir to an Augustus, [...] each of the new Caesars adopted the senior Augustus' nomen after their own [...], in conjunction with the praenomen of their immediate superior. So Galerius Maximianus, Diocletian's Caesar, became C. Galerius Valerius Maximianus and Flavius Constantius, Caesar to Maximian, became M. Flavius Valerius Constantius.

So, Constantius was a Flavius to begin with. Probably this means that there is no way to trace his name any further back, as we know next to nothing about his background and family (except that unhelpful probably-fake genealogy).

Salway's paper mentions a soldier by the name Flavius Euclides, by the way.

P.S. The absence of pre-nomen is not a mistake. According to Salway's theory the "New Romans" (i.e. those enfranchised in 212 by Caracalla) did not take to the use of pre-nomen outside of official documents (where most people were called M. Aurelius Something anyway, like our friend Flavius Euclides who was officially listed as M. Aurelius Flavius Euclides in his unit's roster). Read the whole paper for more fun stuff about names.