Linked from
The 27 pages that link to Roman imperial succession, each with the reason it gives.
Praetorian GuardRelated: The Guard’s support could influence who claimed the throne.
Flavian dynastyRelated: The transfer from Vespasian to his sons tested dynastic succession.
CaligulaNarrower topic: Caligula’s killing left no settled rule for choosing the next emperor.
Barracks emperorRelated: No settled succession rule left armies able to promote rival claimants.