Rome collapses in the Year of the Four Emperors

[octoberman]

The Year of the Four Emperors, AD 69, was the first civil war of the Roman Empire, caused by the assassination of Nero during which four emperors ruled in succession: Galba, Otho, Vitellius, and Vespasian. The period witnessed several rebellions and claimants, with shifting allegiances and widespread turmoil in Rome and the provinces during which the Jews and the Batavi rebelled. Yet Vespasian stabilized the Empire. But what if he is failed and the Parthian empire and the barbarians took advantage of this collapsing the Roman empire ?

 

[Metempsychosis]

What do you mean by collapse? Because the Roman war machine is still at its height, and its institutions would still seek a single authority to fill that vacuum. If the army generals fail to march on Rome, it's more likely that the Senate will try to seize authority and elect one of its members as Emperor.

 

[Lalli]

Bit correction on OP: Whole mess didn't begun because of Nero's assassination. Mess begun already before his death and he commited suicide on early stages.

But it is not likely that Roman Empire would collapse that early. It was far too strong to do that and army was mostly loyal to central authority. Senate would eventually manage to get emperor if any military commander can't do that with force. Yes, there was some local revolts like in Judea and Batavia but these seem being ratherly nuances not some serious affairs which would had threatened existence of the empire.

 

[octoberman]

the Roman war machine is still at its height,

No it peaked under Constantine

 

[Metempsychosis]

No it peaked under Constantine

How was the reign of Constantine the peak of the Roman military?

 

[Mildtryth]

How was the reign of Constantine the peak of the Roman military?

I think he's judging it on the basis of number of soldiers alone, but remember that numbers don't equate effectiveness (if anything, the army seems to have grown less effective over that century), and that many scholars have reason to favor a lower estimate of 4th century army size.

 

[Lalli]

No it peaked under Constantine

Could you clarify? Yes, perhaps it was bigger but it doesn't mean that army would be better. And legions were on that time becoming notoriously disloyal for central government (that what on that time was yet existing) and it couldn't really hold any control on borders regions speciality against Germanic tribes.

 

[octoberman]

Could you clarify? Yes, perhaps it was bigger but it doesn't mean that army would be better. And legions were on that time becoming notoriously disloyal for central government (that what on that time was yet existing) and it couldn't really hold any control on borders regions speciality against Germanic tribes.

Rome had much superior cavalry, organization,border defences and mobility

 

[Metempsychosis]

Rome had much superior cavalry, organization,border defences and mobility

Better cavalry, mobility, and border defences, but for an unwieldy empire in vast amounts of debt and on the defensive against Germanic tribes that knew Roman ways well. You are forgetting the context of this.

The Principate as it existed was too united, and its institutions as established by Augustus too strong, to collapse in a year. If it were a protracted interregnum lasting many years, maybe Rome would collapse completely in the worst scenario, but as it stood in the Year of the Four Emperors, Rome had too many advantages to immediately fall.

 

[avernite]

I would agree with the other posters - It took a century or more of Roman neighbours getting stronger, making inroads as foederati or raiders, expanding their influence, and THEN conquering huge swathes of the Empire (and even then the Empire didn't get mortally wounded until the Sassanid-then-Arab invasions, only permanently shrunk). In the year of the four emperors, that doesn't exist yet.

Parthia could certainly conquer a bunch of Roman stuff, in an extreme case even the whole old Persian empire, the Batavi could seize the lands around the mouth of the Rhine, the Jews could be independent or a Parthian client, but... that still doesn't destroy Rome. Rome would still hold Italy, Iberia, Greece and North Africa (and probably Gaul, Dalmatia/Balkan, Britain - but I suppose there are utter disasters where they lose that).

 

[not livius]

The Year of the Four Emperors, AD 69, was the first civil war of the Roman Empire, caused by the assassination of Nero during which four emperors ruled in succession: Galba, Otho, Vitellius, and Vespasian. The period witnessed several rebellions and claimants, with shifting allegiances and widespread turmoil in Rome and the provinces during which the Jews and the Batavi rebelled. Yet Vespasian stabilized the Empire. But what if he is failed and the Parthian empire and the barbarians took advantage of this collapsing the Roman empire ?

I think this is really unlikely. It doesn't matter which of the claimants win in 68; the Principate and the Empire are strong enough that it's hard to see a setback that Rome couldn't recover from. The Batavians might dislodge Roman control in northern Germania for a little while but I can't really see them as a threat to Gaul in the longer term. Titus is basically committed in Judea no matter what, and if there was a Parthian attempt on Syria Vespasian would come out of Alexandria. I guess in this TL we say, that happens, Vespasian loses in Syria along with Titus' legions -- then Primus and Mucianus have to turn around and attack from Asia Minor. I could see Rome losing a chunk of Syria, probably Armenia becoming part of Parthia proper, assuming the worst case, but it's really hard to see Parthia taking more than that. And Rome still has Italy, Gaul, the Spanish provinces, North Africa, Egypt, Greece, Asia... The thing is, someone is going to be emperor at the end of this, and he is going to want to re-establish Roman control over at least some of this lost territory. And given the military resources Rome has, when the emperor wants to use them, he should be able to.

 

[bguy]

I think this is really unlikely. It doesn't matter which of the claimants win in 68; the Principate and the Empire are strong enough that it's hard to see a setback that Rome couldn't recover from. The Batavians might dislodge Roman control in northern Germania for a little while but I can't really see them as a threat to Gaul in the longer term.

Is a Batavian rebellion likely to stay limited to just the Batavians though? (And especially if Vitellius pulls additional troops out of the Rhine to reinforce his army in Italy, which I think he will pretty much have to do to beat the Flavians.) The Trevari and Lingones might not join with the Batavians (as they did IOTL), in a Vitellius wins timeline as they seemed to have good relations with him, but conversely a Vitellian victory in Italy might see the Aeudi, Arveni, and Sequani join the revolt as all of those tribes had supported (and been rewarded by) Galba and thus had reason to fear Vitellius.

Titus is basically committed in Judea no matter what, and if there was a Parthian attempt on Syria Vespasian would come out of Alexandria. I guess in this TL we say, that happens, Vespasian loses in Syria along with Titus' legions -- then Primus and Mucianus have to turn around and attack from Asia Minor.

I don't see the Parthians attacking unless the Flavian armies in Italy have already been defeated. (Which is not impossible. The Vitellians had a chance to defeat the Flavians in detail thanks to Primus going off half cocked and advancing into Italy with only two legions rather than waiting for Mucianus' army to arrive, but the opportunity was lost due to the treachery of the Vitellian army commander Aulus Caecina Alienus. If Alienus isn't in command of the Vitellian army though or just decides he is better off sticking with Vitellius then you could see the Vitellians wipe out Primus before he gets reinforced, and at that point a fight between the Vitellians and Mucianus' army could go either way.

I could see Rome losing a chunk of Syria, probably Armenia becoming part of Parthia proper, assuming the worst case, but it's really hard to see Parthia taking more than that.

What would stop the Parthians from taking Cilicia and the Armenians from taking Pontus? Rome didn't really have any legions in Asia Minor at this point, so if Vespasian's army gets defeated in Syria, and the Vitellians and Mucianus' army wreck each other in Italy, then there isn't much to hold back the Parthians (at least until the Alans attack them in a couple of years.)

And Rome still has Italy, Gaul, the Spanish provinces, North Africa, Egypt, Greece, Asia...

Italy, Spain, and Asia yes.

Greece-yes though given that the Sarmatians will attack in force across the frozen Danube in 70 AD, Greece is not really a source of additional strength for Rome at this time but is rather another obligation to defend when Rome already has a lot of its plate.

Gaul-I'm not so sure about. As mentioned above I think there's a good chance that the Aeudi, Arveni, and Sequani will join the Batavian revolt, and if that happens Rome is in a lot of trouble in Gaul. (And will the Trevari and Lingones stay loyal to Rome if it looks like the Romans are on the run?)

Egypt-not sure about this one either. If the Flavians lose in Syria they are likely to retreat into Egypt and fortify the blazes out of it. The Roman world could then end up divided between a Vitellian controlled Italy and a Flavian controlled Egypt (which might leave both factions too weakened to unify the empire.)

North Africa-probably. Though if the Flavians manage to solidify their position in Egypt, they will probably then try to take Africa (with an eye to cutting Rome's grain supply), so Africa could become seriously contested.

So while I agree with you that a complete collapse of the Roman Empire is very unlikely at this point, I could see Rome losing significant territory in both Gaul and the east that it will have a very hard time reclaiming.