Among the first acts of Claudius was to stabilize his position and that of the dynasty that had suffered so terribly under Sejanus, Tiberius and Caligula. First he adopted the name of the imperial house, changing from Tiberius Claudius Nero Germanicus simply to Claudius Caesar Augustus. This was more than a case of changing names, however. Claudius did have direct relation to Augustus (through his sister Octavia) and therefore to Julius Caesar (through his sister Julia). By adopting the nomenclature he was more readily identified as a proper heir and legitimate ruler. He also had his grandmother Livia (mother of Tiberius) deified and recalled his two nieces, Julia and Agrippina, the one that he would eventually marry, from exile. Just prior to his rise to the throne, his young wife Messallina bore him a daughter named Octavia and a son who would eventually be called Britannicus.
While Claudius is probably best known for his invasion of Britain, some other events or imperial policies played a significant role in how he was remembered. His relationship with the Senate and the Roman aristocracy was off to a poor start from the beginning, thanks to the interference of the Praetorians. However, the policies of provincial inclusion and Romanization (as vital as they were to the health of the empire) were terribly unpopular in the Senate. Despite the great foresight in bringing Gauls and other provincial Celts into the Roman circle of citizenship and upper society (thereby 'Romanizing 'them), the elite scoffed at such ridiculous gestures. This gesture, however, not only brought Celtic aristocracy closer into ties with Roman authority (trickling down to the tribes of Gaul and Hispania), it likely gave great hope to other provincials of someday achieving the benefits of citizenship. It could be argued that this act is among the most important of the early Principate.
Much like his uncle Tiberius, Claudius proved to be a solid provincial administrator despite his troubles with Roman aristocracy. Under his watch several client kingdoms were annexed, thus circumventing the Augustan policy of non expansion, but only doing so with territory already considered Roman. Among these, the official annexation of Mauretania (though the process was begun under Caligula), Noricum, Lycia & Pamphylia, and Thracia was completed. Judaea too came under direct Roman rule with the death of Herod in AD 44. Of course, perhaps the most important event in the reign of Claudius was the conquest of Britain, but that will be addressed in the following chapter.
Though Claudius has been given credit for partially centralizing Roman government (credit that is largely being proven to be untrue), he certainly did dabble in some very minute details of his administration. He apparently saw the courts, and judging as a vital component of imperial duty. While applause can be given to his devotion and fulfillment of that duty his performance was another matter altogether. He was almost obsessed with spending time in court and ignored various festivals and celebrations of note in order to be present. He was accused of completely ignoring one side of a case, or for being particularly brutal in doling out punishments. Perhaps worst of all, Claudius adopted a policy of hearing many cases privately, with only the input of his own advisors to help sort things out. Therein lied the problem; his advisors were reviled freedmen who, in the view of the Roman social and political elite, had no business achieving such a station of importance.
These freedmen gained great influence over Claudius, along with his wives, but partly because there were few in the Senate who offered loyalty or support to him. While freedmen were a regular part of Imperial and elite households, maintaining positions of some import, no other emperor before or after relied upon them so heavily. This was revolting to the Senate and helps make clear why he was so widely despised. Even though it seems that men like Narcissus, Polybius, and Palla slowly wielded less and less power over time throughout Claudius reign, it's seemingly only because his 4th wife Agrippina filled that role in later years. To the Senate and later generations of Romans, this was merely a continuation of the mockery of Claudius' reign.
Even the ancients, fully understanding that they despised Claudius, still give a complimentary account of his public works achievements. The vital aqueducts, Aqua Claudia and Aqua Anio Novus, were completed during his rule. While both are some of the most spectacular visible ruins today, the Anio Novus was the longest and tallest of its day. In addition to these, Claudius continued his ventures into the public waterways building a new port, aptly named Portus, near Ostia. While the draining of the Fucine Lake turned into an enormous project and ultimately terrible outcome, it was among the most grand of all ancient Roman engineering attempts. Additionally, he introduced three new letters to the Latin alphabet (for the sounds v, ps, y) but these were excluded from use and mostly forgotten shortly after his death.
Among the biggest challenges for Claudius, despite the animosity of contemporaries, was winning over and maintaining the loyalty of the legions. His continuation of Caligula's war in Mauretania and eventual annexation helped establish some military credential, but events would show that Claudius needed far more. In AD 42 the governor of Dalmatia, L. Arruntius Scribonianus, revolted against Claudius with the two legions under his command, at the instigation of some prominent Senators. Though the revolt would only last 4 days before the legions returned their loyalty to the Emperor the case was clear that Claudius had trouble looming on the horizon. After conducting a series of trial resulting in the death of 35 Senators and a couple hundred Equites as a result (certainly further alienating him from the aristocracy) Claudius looked to potential military glory to solve his problems. A campaign was planned for AD 43 that would achieve this goal, bring vast mineral wealth (tin, iron, etc.) within Roman control, and stretch the empire to the very limits of the western world.