Which Roman Emperor invaded Britain in AD 43?

The Roman Emperor who invaded Britain in AD 43 was Claudius. This military campaign marked the beginning of a significant phase in the Roman conquest of Britain, which ultimately led to the establishment of Roman rule over a large part of the island.

Claudius's invasion was notable for several reasons. It was characterized by a well-coordinated military strategy aimed at subduing various tribes in Britain. His efforts were partly to prove his capability as a ruler, as he had faced skepticism about his leadership prior to this campaign. The invasion established Roman control over key areas, including the south-east of England, and laid the groundwork for future expansion and Romanization throughout Britain.

In contrast, other figures mentioned in the options either did not participate in a British invasion or were involved in different contexts. For instance, Julius Caesar conducted expeditions in 55 and 54 BC but did not fully invade and establish permanent control, and Augustus focused on consolidating and expanding territories in other regions rather than directly invading Britain. Nero, on the other hand, reigned much later and did not engage in any significant military campaigns in Britain. Thus, Claudius's role in AD 43 is a pivotal moment in Roman history and British history alike.