Servius Tullius was the sixth of the Roman kings. At first he had his own daughters married to the two sons of Tarquinius, in the hope to prevent a similar fate as Tarquinius. He reinforced his position by winning a war against Veii and bringing home a lot of spoils.
Next he instituted a tax system called census. Every man had to have his properties taxed by one of the two censors. Depending on their estimated property people were divided into classes.
Based on these classes their place in the Roman army was also determined.
Centuries of the first class
Who owned more than 100,000 asses was to serve in one of the eighty centuries of the first class. 40 centuries held seniors (46-60yrs) and 40 juniors (17-45yrs).
They had to bring their own armament: helmet,round shield, greaves, a coat of mail, a spear and a sword.
Two centuries of unarmed carpenters, who were to work the engines of wars, were added to the first class.
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Similar twenty centuries of the second class were enrolled with men who owned between 75,000 and 100,000 asses. They a to bring the same equipment without the chain mail and a buckler instead of a shield.
Identical were formed twenty centuries of the third class for those who owned at least 50,000 asses. The equipment was equal to the second class.
Who owned at least 25,000 asses was divided into one of the 25 centuries of the fourth class. Their armament consisted of a spear and a short javelin.
The fifth class consisted of 27 + 3 centuries for supernumeraries , horn blowers and trumpeters. They were armed with slings and stones.
One had to own a property worth 11.000+ to be divided in one of these centuries.
ProletariansEveryone who owned less, was exempted from military services and was divided into one single century.
The cavalry was expanded to 18 centuries en enrolled with high ranking men. The horses were paid for by the state and a group of widows had to pay for the maintenance of the horses.
Stone wallHe expanded the city and is said to have built the stone wall around Rome, though the remains of thewall arer of later date
After several years the Tarquinius' son incited by his wife, Servius' daughter, murdered Servius and seized power. He would become the seventh king of Rome: Tarquinius Superbus