The Tetrarchic Solution

As previously discussed, by 293 Diocletian and Maximian had long been troubled by the problem of regional rebellion. Specifically, Carausius had survived Maximian’s attempt to

161 _{Division of power through special commands: See also Altmayer (2014) 187-189, with 189 on Probus’ failures.}

Priscus: ILS 9005; PEuphr. 1; Zos. 1.19.2, 20.2; PIR2 _{I 488; Johne, Hartmann & Gerhardt (2008) 1178-1179; Ando}

(2012) 115-116; Potter (2014) 235; see also IGRom. 3.1201-2. Severianus: CJ 2.26.3; Zos. 1.19.2; Ando 117-118; Potter 235. Decius: Zos. 1.21.2; PIR2 _{M 520; Huttner (2008) 201-202; Johne, Hartmann & Gerhardt 1162; Mennen}

(2011) 25, 142-143. Octavianus: ILS 2774 = CIL 8.12296; PIR2 _{C 1408; Johne, Hartmann & Gerhardt 1139.}

Ingenuus: Aur. Vict. Caes. 33.2; HA, Tyr. Trig. 9.1; Mennen (2011) 216-217. Postumus: Zos. 1.38.2; Zon. 12.24; HA, Tyr. Trig. 3.9; Mennen 220 n. 106. Odaenathus: Mennen 224-226 with n. 135. Marcellinus: Zos. 1.60.1-61.1;

PLRE 1 Marcellinus 1; 2; 17; Watson (1999) 79, 167; Hartmann (2001) 393; Altmayer 92, 187-188. Lupus: ILS

1210; PLRE 1 Lupus 5; Christol (1986) 115-116, 133, 263-270; Hartmann 192 n. 109, 393; Kreucher (2003) 199- 200; Johne, Hartmann & Gerhardt 1180; Altmayer 187-188; cf. Watson 164-165; Potter 266. Saturninus: Jer. Chron. 222 (magister exercitus); Jord. Rom. 293 (magister militum); Sync. 723 (CSHB 22) (στρατοπεδάρχης); Altmayer 188-189; see also HA, Firm. 7.2; Malal. 302 (CSHB 32); cf. Zos. 1.66.1; PLRE 1 Saturninus 12; Barnes (1972) 171- 172; Christol 203; Kreucher (2003) 173-174; (2008) 412-413; Kienast (2011) 256. Carus’ command: Zos. 1.71.4-5 = Joh. Ant. fragm. 160 (FHG 4, p. 600). Carus’ usurpation: Zos. 1.71.4-5; Petr. Patr. fragm. 197 (Banchich) = Anon.

Cont. fragm. 11 (FHG 4, p. 198); Zon. 12.29; cf. Aur. Vict. Caes. 37.4; Eutr. 9.17; Jer. Chron. 224; HA, Prob. 21.2-

3, Car. 1.3, 6.1-2; Epit. 37.4; Oros. 7.23.6; Malal. 302 (CSHB 32). For a discussion of Carus’ command and usurpation, see Altmayer 57-66, 188-189. For possibly unhistorical special commands, see HA, Aur. 11.4, 17.3 (cf. 18.1), Firm. 7.2, Prob. 7.4.

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recover Britain and had re-established his continental dominion, leaving the Augusti concerned for the survival of their regime. Although Carausius and the Augusti had now made a truce, the peace had resulted from Carausius’ victories, which had thus undermined the authority of Diocletian and Maximian. Maximian had failed to defeat a usurper within his half of the empire, and Diocletian had failed to protect his right to co-opt new emperors. While they avoided

acknowledging Carausius’ claims to legitimacy and collegiality, the cessation of hostilities and Maximian’s possible cooperation with Carausius against German pirates betrayed weakness. The problem was twofold. Carausius’ ongoing survival and martial success against both pirates and Romans posed a direct threat to the Dyarchs. Carausius might wish to press his claim to

legitimacy by marching towards the Rhine, where he might win over legions in the same way that the British and Gallo-Rhenish legions collaborated under the Gallic emperors. Legions on the Rhine might instead declare allegiance to the militarily successful Carausius out of their own volition, since, as we have seen, military success was an especially important imperial trait during the later third century. On the other hand, Carausius’ success was a potential

encouragement to provincial rebellions elsewhere, and it represented the persistent problem of trying to control the armies and their officers. For the Dyarchs, it could not but recall the

imperial divisions of previous decades. Diocletian and Maximian could give formal recognition to Carausius’ claims, and in doing so counter-act the direct threat he posed, but this would only worsen the problem of regional rebellion, especially that of the military, that Carausius’ success encouraged and represented.

There was surely anxiety about the army. With Maximian having been born c. 250, and Diocletian c. 240, the Augusti had grown up during a time in which regional military rebellion was a major problem. They had scaled the ranks during the years of imperial division, and had participated in civil war and separatism.162 Diocletian had himself launched a usurpation against a physically distant Carinus, and his command over the domestici in 284 perhaps suggests that in 282 he had supported Carus when that emperor usurped against Probus. Diocletian and

162 _{On the ages of Diocletian and Maximian, see Paneg. 11(3).7.6-7; Epit. 39.7, 40.11; Enßlin (1948) 2421; PLRE 1}

Diocletianus 2; Barnes (1982) 30-31, 32; Rougé (1992) 79. The Epitome states that Diocletian was 68 when he died and implies that he died in early 313, which places his birth in the mid-240s. It also reports that Maximian was 60 when he died in 310, hence c. 250. However, the panegyrist in 291 elaborately celebrates that the Augusti have overcome their difference in age, which may suggest that the Epitome’s author or a copyist was mistaken regarding the age of Diocletian.

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Maximian had attained their positions thanks to the problem of military rebellion, and they had every reason to worry that they would be next in a long line of emperors to be overthrown by the army. Indeed, Diocletian’s well-known division of the provinces may have been partly motivated by a desire to reduce the competences of generals and governors.163 Diocletian’s use of the coin legend Concordia Militum (‘harmony of the army’) may be significant. Coins proclaiming the army’s concordia only appear in large quantities during the tumultuous years of the middle and later third century. They were most frequently minted early within an emperor’s reign or during civil war, and they were especially popular among emperors lacking military credentials. It would appear then that the legend hints at concern for military loyalty, and it is thus fitting that in 291 and 292, the imperial mint at Heraclea issued a coin with this legend in numbers that have rendered it a common find.164 It is therefore likely that the Augusti were anxious about the army.

It was argued above that, in the later third century the presence of an emperor was a powerful factor in preserving loyalty to a regime, and that regional military populations demanded a present emperor both out of rational concerns and irrational entitlement. The Tetrarchy fits well as a solution to this problem. If the Caesars were both appointed on 1 March, their co-option was a carefully stage-managed endeavour. In one half of the empire Diocletian appointed Galerius his Caesar, while in the other half Maximian did the same for Constantius, and the four rulers then parted ways to different militarized regions of the empire. Constantius was active in Gaul, the Rhineland and, upon its recovery, Britain. Maximian spent most of his time in northern Italy, and thus was also near Raetia and Noricum. Diocletian and Galerius were forced to deal with military emergencies on the eastern frontier and in Egypt from c. 296-299, but from c. 293-296, Diocletian was in the Balkans while Galerius was in the east, and from c. 299-305, Galerius was in the Balkans while Diocletian divided most of his time between Egypt, the Syrian provinces and Asia Minor.165

163 _{Harries (2012) 50-52; Kulikowski (2016) 196. The division of provinces: Barnes (1982) 201-225; (1996) 548-}

550.

164 _{RIC 5.2 Diocletian 284. Concordia Militum and imperial anxiety: Hedlund (2008) 98-101; Hebblewhite (2017)}

198-202.

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Lactantius, Praxagoras and Aurelius Victor describe a fourfold division of the empire, but this does not appear the case.166 _{Lactantius’ claim forms part of his invective, in which}

Diocletian overturned the empire, and Praxagoras and Victor lived through times when there were clearer political divisions between the territories of co-emperors. The Dyarchic panegyrists had celebrated the empire as an imperium singulare (10(2).11.1-2) and patrimonium indiuisum (11(3).6.3-7.3), which might be empty praise, but we have seen that Diocletian and Galerius were flexible in where they were located. Moreover, from 302-303 and in 305, Diocletian and Galerius were both in Nicomedia, in 303 or 304, Diocletian inspected the Danube frontier while Galerius was also in the Balkans, and in 295 or 296, Maximian supervised the Rhine while Constantius campaigned in Britain.167

There appears to have existed a division of sorts between Diocletian’s east and

Maximian’s west. The second and fourth persecution edicts against the Christians (303-304) do not seem to have been effectively promulgated in the west. The same perhaps applies to the prices edict (301), of which every copy bar one has been found in the empire’s eastern half, and the exception seems to have originated in the east, although provincial initiative may have more to do with this, since the eastern examples are limited to three provinces.168 There are also only two recorded instances from the First Tetrarchy in which an eastern or western emperor entered the other half of the empire: Diocletian visited Italy from 303-304, and Lactantius reports a meeting between Maximian and Galerius without giving a location (DMP 18.1).169 _However,

there is no evidence for a formal division. Every preserved edict of the First Tetrarchy stemmed from the court of the senior emperor Diocletian, except perhaps the Damascus incest edict (295), which, based on date and location, may have been issued by Galerius on the orders of Diocletian,

166 _{Lact. DMP 7.2 (fourfold division), 8.3 (Maximian controlled Italy, Spain and Africa); Praxagoras in FGrH 2B,}

219.1 (Constantius ruled Britain, Maximian Rome, Italy and Sicily, Galerius Greece, Macedon, Thrace and Asia Minor, Diocletian Bithynia, Arabia, Egypt and Libya); Aur. Vict. Caes. 39.30 (fourfold division, with Gaul beyond the Alps entrusted to Constantius, Africa and Italy to Maximian, the Balkans to Galerius and the rest to Diocletian); see also Jul. Or. 2.51d (Maximian governed Rome, Italy, Africa, Sardinia and Sicily, Constantius Gaul, Spain and the islands of the Ocean).

167 _{No formal division: Seston (1946) 231-247; De Ste Croix (1954) 105-106; Williams (1985) 65; Nixon & Rodgers}

(1994) 66 n. 31; Leadbetter (1998a) 225; (2009) 68-73; Potter (2014) 278; cf. Barnes (1982) 196-197. On the panegyrics, see also Paneg. 10(2).9.4, 10.1. Diocletian and Galerius in Nicomedia: (302-303) Lact. DMP 10.6-14.7; Eus. HE 8.5; (305) Lact. DMP 18-19. Diocletian on the Danube: (303) CJ 5.73.4; (304) Lact. DMP 17.4; Barnes (1976a) 191; (1982) 56 n. 43. Maximian on the Rhine: Paneg. 8(5).13.3.

168 _{Persecution edicts: De Ste Croix (1954) 84-96, 105-106; Keresztes (1983) 384-390; Corcoran (2000a) 181-182.}

Prices edict: Corcoran 229-231; cf. Ermatinger (1996) 91-92.

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and was perhaps local in motive and scope.170 _{Although Africa was within Maximian’s half of}

the empire, Diocletian responded to a petition from that province in 293 (FIRA2 _{2.665) and a}

letter on the Manichees from Africa’s proconsul probably in 302 (Coll. 15.3). The latter might be explained by Diocletian’s knowledge of the Manichees as the eastern Augustus, but such

legislation certainly attests to fluidity in administration.171 Furthermore, the two praetorian prefects were formally a college, and therefore neither was formally associated with an Augustus.172

Despite the absence of a fourfold division, the Caesars were not without power. The Caesars had the capacity to lead armies, and they conducted the most important campaigns of the period; the war against the British regime and the Persian war. Furthermore, they had some administrative authority. As previously noted, there were two praetorian prefects, and thus the Caesars did not have prefects of their own.173 Nevertheless, one would expect the Caesars to have some administrative power, and there is evidence for this. Constantius resettled the Franks (Paneg. 8(5).8.4, 21.1-2), had something of a court (Paneg. 9(4).14.1), and had a magister

epistularum, since he sent a letter to one Eumenius (Paneg. 9(4).13-14). This Eumenius,

formerly a magister memoriae (6.2, 11.2), Constantius appointed as the praeceptor of a school with a salary of 600,000 sesterces (13-14). Admittedly, Constantius referred to Maximian in making the appointment (6.2), either because he needed the latter’s permission or because

Eumenius was Maximian’s magister memoriae.174 _{Maximian could issue rescripts, and it appears}

that the Caesars, who were named on all constitutions, had the same competence.175 _{A rescript}

responding to an unknown petitioner on 5 Aug. 294 in Agrippina must be a constitution of Constantius if Agrippinae refers to Cologne (CJ 5.12.21).176 Four private rescripts from Antioch

170 _{Corcoran (2000a) 270. Incest edict: Coll.6.4; Corcoran (2000b) 9-14. Galerius as the issuer: Barnes (1982) 62-63}

n. 76; Corcoran (2000a) 173 n. 14, 270; cf. Leadbetter (2002) 88 n. 32. See also Lact. DMP 15.6, who claims that Diocletian and Galerius, in issuing the persecution edicts, did not consult Maximian and Constantius, who were then ordered to comply. Barnes (2011) 64-65 argues that both Augusti could issue edicts, but his examples date to the Second Tetrarchy.

171 _{Maximian in Africa: Barnes (1982) 59. On the Manichees letter, see Corcoran (2000a) 135-136, 271.}

172 _{A college of two praetorian prefects: ILS 8929; ILS 619 = CIL 6.1125; AE 1987.456; Chastagnol (1989); Barnes}

(1996) 546-547; Corcoran (2000a) 88-89; see also Potter (2013) 109-110.

173 _{Leadbetter (2009) 70-71.}

174 _{Nixon & Rodgers (1994) 158 n. 26; Corcoran (2000a) 268-269; Rees (2002) 141-142, 146.}

175 _{On Maximian, see the constitutions used to reconstruct his movements in Barnes (1982) 57-60 (e.g. FV 41, 271,}

282, 292, 313). Named on all constitutions: Kolb (1987) 43.

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in 294 might suggest Galerius was the issuer, but there are grounds for emending the locations to Pantichium or Anchialos, which matches Diocletian’s itinerary and supposes that less familiar names were altered into more familiar ones.177 CJ 2.12.20 was supposedly issued at ‘Demesso’ to the praeses Verinus in 294, and if the location is corrected to Damascus, it would necessitate Galerius as the issuer. However, during the Second Tetrarchy, Maximinus sent a letter to a Verinus when he was Caesar in the east, which might warrant emending the year (CJ 3.12.1).178 The Caesars had some authority concerning the persecution, since Constantius permitted the destruction of churches and chose not to do more (Lact. DMP 15.6-16.1).179

It must be admitted that Constantius II claimed that the Tetrarchic Caesars ‘acted in the fashion of servants (apparitores), not residing in one place, but travelling hither and thither’ (Amm. 14.11.10). This was how Constantius wished his Caesar to act, and Galerius’ movements attest to his claim.180 Moreover, Diocletian travelled to Galerius on the eastern frontier to

determine peace terms for the Persians (Petr. Patr. fragm. 202 (Banchich)), which suggests that Diocletian’s presence was needed for such an important treaty. But their deliberation and the fact that they sent the embassy ‘in common’ (κοινῇ) shows that Galerius’ authority was maintained either in practice or in the public eye.181 Julian considered Diocletian to be self-effacing (Caes. 315a-b), and although later authors reported that Diocletian, after Galerius’ defeat by the Persians, made the Caesar run in front of his carriage for nearly a mile, this is a fiction.182 _It

would have been ludicrous for Diocletian to so humiliate his heir apparent, and Lactantius does not mention it, which he could have made suit his narrative of a Galerius discontent with being Caesar.183 Rather, hostile sources probably misinterpreted a show of deference during an

aduentus ceremony, or a symbolic display of Galerius’ determination to succeed.184 The

177 _{CJ 4.29.18, 5.12.24-25, 8.31.2, with Corcoran (2000a) 272-273.}

178 _{‘Demesso’ and Verinus: Corcoran (2000a) 131, 143, 271; see also CJ 7.16.40. On the legislative capacity of the}

Caesars, see Corcoran 271-274.

179 _{De Ste Croix (1954) 105-106. Eus. HE 8.13.12-13, Append. 4 and VC 1.13.3 claims that Constantius did not}

engage in the persecution, but in MP 13.12 he states that the persecution in the west, including Gaul, lasted for less than two years.

180 _{Amm. 14.11.10: Quibus subserebat non adeo vetus exemplum quod Diocletiano et eius collegae ut apparitores}

Caesares non resides, sed ultro citroque discurrentes obtemperabant...

181 _{Petr. Patr. fragm. 202 (Banchich) = fragm. 14 (FHG 4, p. 189). Cf. Leadbetter (2009) 71.} 182 _{Carriage story: Eutr. 9.24; Festus, Brev. 25; Amm. 14.11.10.}

183 _{Cf. Kolb (1987) 136.}

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evidence ultimately shows that the Caesars had military and administrative power, with their governance based on their proximity to subjects.185

Indeed, the honours enjoyed by the Caesars corresponded to an active role in leadership. Unlike most Caesars, they received cognomina deuictarum gentium for their own victories and they shared in the cognomina won by others. They received tribunician power, and although epigraphy was in decline in the later third century, by which such power would be evidenced, among third-century Caesars tribunician power is otherwise attested only for the sons of Decius and Carus. According with their tribunician power, the Caesars received a count of their regnal years and they celebrated the uota of their rule. A panegyric honours them as imperatores (Paneg. 8(5).3.1, 15.4), and they received the auspices and the right to the salutation dominus

noster.186

There is no doubt that they had the military competence with which to reward and lead on campaigns the military units within their spheres of activity, and since they had some

administrative power, they could be useful senior administrators. In this way, the dominion of the Tetrarchs was based upon proximity and hierarchy. The Tetrarchs legislated for the areas of the empire to which they were proximate, but the Augusti enjoyed greater power than their Caesars, and Diocletian retained the greatest administrative competence as the first-ranking Augustus. The empire’s northwest was served by a present Constantius Caesar, Italy, Africa and Raetia by Maximian, and the east and the Balkans divided between Diocletian and Galerius, although emergencies forced both into the east from c. 296-299. This positioning of the rulers also ensured that any external enemy would soon find itself facing off against an emperor. Galerius could keep watch over the units stationed along the lengthy Danube frontier.

Constantius could do the same along the shorter Rhine frontier while attending to the troubled provinces in Gaul and Britain. Diocletian could focus more attention on the eastern frontier and grain-rich and troubled Egypt. Maximian, who seems to have spent most of the First Tetrarchy in northern Italy, could 1) closely attend to the needs of the units based there and, like Carus under

185 _{Governance based on proximity: Potter (2014) 278. The power of the Caesars: Barnes (1996) 546-548; Corcoran}

(2000a) 268-274; Bowman (2005) 75; Leadbetter (2009) 71-72, 80 n. 182; Neri (2013) 664.

186 _{Honours: Kolb (1987) 85. The Caesars and tribunician power: Kolb 34-35, who argues that Maximian also had}

this honour as Caesar; Leadbetter (1998a) 219. The decline in epigraphy: MacMullen (1982). Regnal years: E.g. RIC 6 Trier 35; Barnes (1982) 28. Previous Caesars and regnal years/uota: Smith (1972) 1064; Kolb 35, 121. Auspices:

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Probus, in Raetia and Noricum; 2) provide closer imperial attention to Rome, Italy, Spain and Africa while leaving the northwest to Constantius, as far as Caesarian powers allowed; and 3) stand between Italy and the Alemanni.187 Maximian had fewer units to concern himself with than his colleagues, who had charge over longer stretches of frontier, but his responsibility to Italy, the city of Rome, the praetorian guard, the senate and grain-rich Africa made up for that, and it should be borne in mind that his Augustan authority, which was surely superior to that of the Caesars and was based on proximity rather than political divisions, would have still been relevant to troops in Gaul and Pannonia.188 The Tetrarchy was thus a carefully-planned scheme of imperial presence for the army and for the empire in general in order to prevent rebellion. This scheme was best achieved with Caesars. When Diocletian sent Maximian to Gaul to defeat the Bagaudae, he sent him in the capacity of Caesar. It surely meant more to the army to have a Caesar in their vicinity than a general with an extraordinary command. We have also seen that generals with extraordinary commands could use their power to usurp. If a general was already honoured with the purple, and an Augustus was his auctor imperii, to whom he should be bound through the pietas (loyalty) owed to one’s benefactor, he was less likely to usurp.189

Such an arrangement explains Maximian’s apparent inaction during much of the First Tetrarchy. Maximian kept guard on the Rhine while Constantius retook Britain, and he

campaigned in Spain and Africa from c. 296-298, but no campaign is attributed to him after the African war.190 _{That the panegyrist in 307 appears to treat the African campaign as his most}

recent achievement confirms his military inactivity (7(6).8.3-6). His most important achievement was that he kept the soldiers contented, undoubtedly taking some on campaign, and otherwise remaining present to provide an interest, symbolic or actual, in their affairs. It is these soldiers who in 307 would throw their support behind Maximian and his son Maxentius rather than remain loyal to their new Augustus Severus.191

Various details strengthen the impression that the appointments were to please the soldiery. The day of the appointments, 1 March, was the traditional beginning of the

187 _{Maximian’s movements and residences: Barnes (1982) 56-60.} 188 _{For the discrepancy: Syvänne (2015) 227.}

189 _{On the co-option of Maximian, see also Williams (1985) 42-43; Altmayer (2014) 186.} 190 _{Maximian’s residences and journeys: Barnes (1982) 56-60.}

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campaigning season and the day of Mars, as well as the beginning of spring, which was symbolic of regeneration.192 _{We can surmise that the Augusti presented their sons-in-law before military}

assemblies that consisted of troops already with the emperors and officer representatives from other legions, since Lactantius describes such an assembly when Galerius co-opted Maximinus in 305 (DMP 19). Indeed, Lactantius claims that Maximinus’ appointment outside Nicomedia was on the same spot as where Galerius had been appointed, which, while we have seen that this is incorrect, shows that the author understood it to be a similar ceremony. The appointees

themselves were adults and military professionals. They could easily conform with the ideal of the military emperor so popular amongst the soldiery, especially during the later third century, and they had the career histories to provide the armies with confidence.