Januarius was born in the Caserta Palace, two years before the death of his father Ferdinand II, the penultimate King of the Two Sicilies.

At the time of the Prince's birth, Ferdinand was already ill and too weak to play with his youngest son as he had done with his previous eleven children.

Pope Pius IX offered the family a residence at Quirinal Palace in Rome as gratitude for their loyalty.

Januarius's mother Maria Theresa took the children who still lived with her at Quirinal Palace and moved them over the Alban Hills to Albano Laziale.

Maria Theresa was also infected and died after atrocious suffering, having refused treatment from a doctor whom she considered to be "liberal."