The Historia Augusta is a collection of biographies written around 400 about third century emperors and would be emperors. The author or authors - mirrored social and political issues from his own time into these biographies and this makes the Historia Augusta problematic as a reliable source. Unfortunately it is almost the only source covering that period. The wiki link below gives full details about the scholarly debates on this work.
Most biographies are short and actually no biographies at all, but hardly more than anecdotes. One such short biography is about Mussius Aemilianus, not to be confused with emperor Aemilianus, who was emperor during three months in 253. It was a time of unrest and various commanders in the Eastern provinces revolted against Emperor Gallienus. All failed and then Aemilianus decided to declare himself emperor . The cause was a revolt in Alexandria and Aemilianus, thinking his life was in danger anyway, gambled – and lost: he was defeated in March 262, captured and strangled.
There is a problem: Aemilianus’ life is also known from a long inscription and Eusebius’ ecclesiastical history and outside this source nothing is known of Aemilianus’ imperial ambitions. Could it be that Gallienus simply put Aemilianus aside under the pretext that he tried to usurp power?
What is interesting in this text is not so much Aemilianus, but the way Egyptians are described: quarrelling about trivialities and easily rioting. What the text does not say is that the burden of taxation was high and that many lived on the brink of starvation. A good excuse for resentment and revolt.
Historia Augusta, Tyranni Triginta 22.
Est hoc familiare populi Aegyptiorum ut velut furiosi ac dementes de levissimis quibusque ad summa rei publicae pericula perducantur; 2 saepe illi ob neglectas salutationes, locum in balneis non concessum, carnem et olera sequestrata, calceamenta servilia et cetera talia usque ad summum rei publicae periculum in seditiones, ita ut armarentur contra eas exercitus, pervenerunt. 3 familiari ergo sibi furore, cum quadam die cuiusdam servus curatoris, qui Alexandriam tunc regebat, militari ob hoc caesus esset quod crepidas suas meliores esse quam militis diceret, collecta multitudo ad domum Aemiliani ducis venit atque eum omni seditionum instrumento et furore persecuta est; ictus est lapidibus, petitus est ferro, nec defuit ullum seditionis telum. 4 qua re coactus Aemilianus sumpsit imperium, cum sciret sibi undecumque pereundum. 5 consenserunt ei Aegyptiacus exercitus, maxime in Gallieni odium. 6 nec eius ad regendam rem publicam vigor defuit, nam Thebaidem totamque Aegyptum peragravit et, quatenus potuit, barbarorum gentes forti auctoritate summovit. 7 Alexander denique vel Alexandrinus (nam incertum id quoque habetur) virtutum merito vocatus est. 8 et cum contra Indos pararet expeditionem, misso Theodoto duce Gallieno iubente dedit poenas, et quidem strangulatus in carcere captivorum veterum more perhibetur.
familiaris -is: usual
levissimis quibusque: whatever trivial
perduco perduxi perductum: to lead, bring
balneum: public bath
olus oleris (n.): vegetable
sequestro (-are): to separate, withhold
carnem et olera sequestrata: probably sequestrata with carnem too. The meaning is vague.
calceamenta servilia: shoes of slaves
seditio –onis (f.): insurrection, revolt
armo (-are): to equip with arms
curator –is: governor
caedo cecidi caesum: to strike, kill
militaris –is (m.): soldier
iacio ieci iactum: hit
ullum telum: any kind of weapon
undecumque: from every side
maxime in Gallieni odium: foremost for their hate of Gallienus
nec eius vigor defuit: nor did he lack the vigor (ei instead of eius is usual)
Thebaiden Aegyptum: large dessert in Upper (= southern) Egypt
peragro: to traverse
quatenus: as far as
summoveo summovi summotum: to expel, drive away
virtutum merito: on account of his virtues
id incertum habetur: this is held uncertain = this is uncertain
Indos: not the people of India, as in the translation below and my recent Dutch translation have, but the Ethiopians or Arabs (cf. Lewis and Short s.v. Indus)
paro: to prepare
misso Theodoto duce Gallieno iubente dedit poenas: general Theodotus being sent he was punished, Gallienus ordening = general Theodotus was sent and he was punished on the order of Gallienus
strangulatus perhibetur: he is said to be strangled
captivorum veterum more: like the captives of old or as is done with old captives?
Translation by David Magie (1921)
It is the wont of the people of Egypt that like madmen and fools they are led by the most trivial matters to become highly dangerous to the commonwealth; 2 for merely because a greeting was omitted, or a place in the baths refused, or meat and vegetables withheld, or on account of the boots of slaves or some other such things, they have broken out into riots, even to the point of becoming highly dangerous to the state, so that troops have been armed to quell them. 3 With their wonted madness, accordingly, on a certain occasion, when the slave of the chief magistrate then governing Alexandria had been killed by a soldier for asserting that his sandals were better than the soldier's, a mob gathered together, and, coming to the house of the general Aemilianus, it assailed him with all the implements and the frenzy usual in riots; he was pelted with stones and attacked with swords, and no kind of weapon used in a riot was lacking. 4 And so Aemilianus was constrained to assume the imperial power, knowing well that he would have to die in any event. 5 To this step the army in Egypt agreed, chiefly out of hatred for Gallienus. 6 He did not, indeed, lack energy for administering public affairs. For he marched through the district of Thebes and, in fact, the whole of Egypt, and to the best of his powers drove back the barbarians with courage and firmness. 7 Finally, he won by his merits the name of Alexander, or else Alexandrinus — for this is considered uncertain. 8 But when he was making ready for a campaign against the people of India, the general Theodotus was sent against him by order of Gallienus, and so he suffered punishment, for it is related that, like the captives of old, he was strangled in prison.
https://en.wikipedia.org/wiki/Mussius_Aemilianus (The German wiki on Aemilianus is far better.)