Roman public religion was a contract. The pax deorum, the settled peace with the gods, was maintained by exact performance of rite, and a run of disasters was read as evidence that the performance had gone wrong somewhere and that the fault must be found and expiated. The first three years of Hannibal's war produced disasters on a scale nothing in Roman memory matched: the Trebia in 218, Lake Trasimene in 217, and at Cannae in 216 the destruction of the largest army Rome had ever fielded.
The response was liturgical as much as military. The senate ordered the decemviri to consult the Sibylline Books, the collection of Greek oracles kept on the Capitol and opened only by decree; a sacred spring was vowed, dedicating the next year's produce to the gods; and lectisternia, banquets at which images of the gods were laid on couches, were held for days. Two Vestal Virgins, Opimia and Floronia, were found to have broken their vows, one being buried alive and the other killing herself, and the pontifex maximus scourged the pontifical secretary who had been involved. Livy then records the rite the Romans themselves called least Roman: a Gaulish man and woman and a Greek man and woman were buried alive in the Forum Boarium.
Livy calls this a sacrifice wholly foreign to Roman practice, and Roman writers afterwards treated it as a measure of how far the terror of that year had gone. An embassy was also sent to consult the oracle at Delphi.