Titus Didius belonged to the plebieangensDidia, which was relatively new in Roman politics. The first known member of the gens was his homonymous father, who passed a sumptuary law when he was tribune of the plebs in 143 BC. From his filiation given in the Fasti Capitolini, we also know that Didius' grandfather was named Sextus.
Titus Didius first appears in history as triumvir monetalis, one of the three men tasked with minting coins, probably in 113 or 112. The reverse of his denarii shows two gladiators fighting. Michael Crawford suggests that it may have been a political promise from Didius to offer gladiatorial shows, should he be elected curule aedile. It is not known whether Didius was subsequently elected.
Two years later in 101 BC, he was elected a praetor. During this time he fought in Macedon, defeating the Scordisci and earning his first triumph upon his return in 100 BC.
Consul (98 BC)
In 98 BC Didius was elected consul alongside Quintus Caecilius Metellus Nepos. Along with restoring the Villa Publica, he enacted a law which disallowed combining two unrelated proposals in one bill.
Proconsul (97–93 BC)
After his term as consul, Didius was assigned to govern the province of Hispania Citerior as a proconsul, where he governed from 97 BC to 93 BC. Nearly his entire proconsular term in Spain was spent at war with the Celtiberi. In the four years Didius governed Spain, he achieved multiple victories and is said to have slain 20,000 Arevaci, quelled the rebellious city of Termes, and besieged Colenda for nine months, after which time the city fell and the women and children were sold into slavery. Didius earned another triumph after slaughtering a colony of "robbers" -- in actuality, poor people who had banded together to subsist through banditry after losing their property. Didius lured them in with promises of land to live on, and when the families assembled within the Roman castra in good faith, he had them all killed. The historian Appian indicates that Didius's exceptional cruelty and treachery caused an even greater uprising which his experienced successor, Gaius Valerius Flaccus, had to put down. The famous Roman rebel Quintus Sertorius served as a military tribune under Titus Didius in Spain. He was awarded the Grass Crown for crushing an insurrection in and around Castulo.