Tullus Hostilius was much like Romulus in his warlike behavior and completely unlike Numa in his lack of respect for the gods. Tullus waged war against Alba Longa, Fidenae, and Veii, thus granting Rome even greater territory and power. It was during Tullus' reign that the city of Alba Longa was completely destroyed and Tullus enslaved the population and sent them back to Rome.

Tullus desired war so much that he even waged another war against the Sabines. With the coming of Tullus’ reign, the Romans lost their desire for peace. Tullus fought so many wars that he completely neglected the worship of the gods. Legend has it that because of this, a plague infected the city, and Tullus himself was among the infected. When Tullus called upon Jupiter and begged assistance, Jupiter responded with a bolt of lightning that burned the king and his house to ashes.

Despite his war-like nature, Tullus Hostilius selected and represented the third group of people to make up Rome’s patrician class consisting of those who had come to Rome seeking asylum and a new life. He also constructed a new home for the Senate, the Curia, which survived for over 500 years after his death. His reign lasted for 31 years. 

Numa reformed the Roman calendar by adjusting it for the solar and lunar year as well as by adding the months of January and February to bring the total number of months to twelve. Numa instituted several of Rome's religious rituals including the Salii, and a flamen maioris to serve as the chief priest to Quirinus, the Flamen Quirinalis. Numa organized the area in and around Rome into districts for easier management. He is also credited with the organization of Rome’s first occupational guilds.

Numa is remembered as the most religious of the kings (surpassing even Romulus), and during his reign, he introduced the flamens, the vestal virgins of Rome, the pontiffs and the College of Pontiffs. Under his administration, temples to Vesta and Janus were constructed. Also during his reign, it was said that a shield from Jupiter fell from the sky with the fate of Rome written on it. Numa ordered eleven copies of the shield to be created and these shields became sacred to the Romans.