Quick questions on Agrippina the Younger's marriage to Claudius and role as Augusta: HSC Ancient History

Roman law (the Lex Iulia de adulteriis, with later jurisprudence) forbade marriage between an uncle and his brother's daughter. The marriage required a senatorial decree.

On the adoption of Nero on 25 February AD 50, Agrippina was granted the title Augusta. The title was unprecedented for a living wife of a reigning emperor.

Claudius had a natural son, Britannicus, born to Messalina in February AD 41. Britannicus was the legitimate heir. Adopting Agrippina's son Lucius Domitius into the imperial family disrupted that succession.

Agrippina also engineered the union of her son with Claudius's daughter. Octavia (born around AD 40) had been previously betrothed to Lucius Junius Silanus. Agrippina arranged for Silanus to be charged with incest with his sister Junia Calvina (a charge brought by the censor Lucius Vitellius, Agrippina's ally). Silanus was expelled from the Senate; he killed himself on the day of Agrippina's marriage to Claudius.

Agrippina's birthplace at Ara Ubiorum on the Rhine was raised to the status of a Roman colony in AD 50 and named for her (Colonia Claudia Ara Agrippinensium). The name survives as the modern city of Cologne. Veterans of the German legions were settled there. The colony was the first founded with the express patronage of an imperial woman.

Agrippina's public profile under Claudius was unprecedented in extent.

Tacitus (Annals 12) records a sequence of removals.

The imperial freedman Marcus Antonius Pallas, finance secretary (a rationibus), was Agrippina's chief ally. He had argued for her marriage to Claudius and now functioned as the channel between her household and the imperial administration. Tacitus (Annals 12.65) describes Pallas as Agrippina's lover (a rumour, not necessarily fact).

Tacitus (Annals 12.64 onwards) reports that by AD 54 Claudius was beginning to regret the marriage and the adoption. The emperor was rumoured to have favoured Britannicus over Nero, and to have spoken of Messalina's children as the true heirs. Whether Tacitus exaggerates is debated. Anthony Barrett argues that the breach was real but not yet decisive when Claudius died.

Tacitus, Annals 12.7. "Henceforth the State was changed, and all things obeyed a woman." This is the dominant ancient verdict.

A two-horse carriage previously restricted to the Vestal Virgins and triumphators. Agrippina rode in it at religious festivals.

Statues of Agrippina were dedicated across the empire. The Sebasteion at Aphrodisias (in Caria, western Asia Minor) preserved a relief showing Agrippina with Claudius.

As noted, jugate portraits with Claudius on the obverse. Some provincial coinage of Asia Minor showed her alone.

Agrippina sat with Claudius (on a separate dais) to receive the captured British king Caratacus and his family in AD 51 (Tacitus, Annals 12.37). Caratacus paid homage to her as well as to the emperor. Tacitus calls this a novelty, "alien to ancestral custom."

The unsuccessful candidate for Claudius's hand, granddaughter of Marcus Lollius and a wealthy heiress. Charged with consulting astrologers about Claudius's marriage. Exiled and forced to suicide.