Caligula (12-41) was the third emperor of Rome. At best, he was one of the most autocratic of Rome's early emperors; at worst, one of the most deranged.

Caligula was born Gaius Julius Caesar Germanicus in Antium (modern Anzio) on Aug. 31, A.D. 12. His mother, Agrippina, was Emperor Augustus's granddaughter, and his father, Germanicus, was Emperor Tiberius's nephew, adopted son, and heir. Gaius was brought up among the soldiers his father commanded on the Rhine. His mother dressed him in the uniform of a Roman legionnaire, and for this reason the soldiers called him Caligula ("Little Boots"), the name by which he is commonly known.

In A.D. 19 Germanicus died. His death was mourned throughout the empire because he was, by all accounts, an honorable and courageous man. After his father's death Caligula lived in Rome, first with his mother, then with Livia (Augustus's wife), and then with...