Claudius was installed by the Praetorian Guard. It was under his administration that the Iceni rebelled under Queen Boudicca. Despite the troubles there, Britain became a province of Rome. Claudius also annexed Mauretania, in North Africa, and divided it into two provinces (Caesariensis and Tingitana), Lycia in Asia Minor, and Thrace (46). Claudius made Judaea and added Iturea to the province of Syria. He allowed his own son Britannicus to be overlooked for the succession in preference to his wife Agrippina's son, Nero. Claudius was a complex figure whom writers satirized after his death.
* Aloys Winterling argues that Caligula was not mad.
"This day in ancient history" caveat: please see Unreliability of Dates.