He spent his early life engaged in historical study, prevented from entering public life by his physical infirmity; he was proclaimed emperor after the murder of Caligula. His reign was noted for its restoration of order after Caligula’s decadence and for its expansion of the Roman Empire, in particular the invasion of Britain in the year 43, in which he personally took part. His fourth wife, Agrippina (15–59 ad), is said to have killed him with a dish of poisoned mushrooms.