When were decemvirs first established in the Roman Republic?
Decemviri
451BC
The decemviri took office in 451BC. Both consuls elect, Appius Claudius Crassinus Inregillensis Sabinus and Titus Genucius Augurinus, resigned. So did the other magistrates and the plebeian tribunes. In compensation for their loss of office, Appius Claudius and Titus Genucius were appointed to the decemviri. So was one of the consuls of the previous year (452 BC), Publius Sestius Capitolinus Vaticanus, because he had put the proposal to the senate despite the opposition of his colleague.  The three envoys were also part of the decemviri.[11] The most influential member was Appius Claudius who, according to Livy, "was the guiding hand in the whole magistracy ... thanks to the favour of the plebs."[12] Each day a different decemvir presided over the magistracy and this man had the twelve lictors (the bodyguards of the consuls) with fasces (bound bundles of rods which were the symbol of supreme authority and sometimes had axes). Their rule was fair and their administration of justice was exemplary. Despite not being subject to appeal, they yielded to one another when an appeal was taken. They drafted their laws on ten bronze tables and presented them to the people, asked for feedback and amended them accordingly. They were approved by the higher popular assembly, the Assembly of the Soldiers. There was a general feeling that two more tables were needed to have a corpus of all Roman law. It was decided to elect a new decemvirate.[13]