There eventually would be twenty years of treachery, massacre, and repudiated treaties as the native tribes of the Iberia Peninsula fought against Roman occupation. The Lusitanians would be defeated only after their leader Viriathus was assassinated in 139 BC. The Celtiberian Wars would end in 133 BC, when Scipio Aemilianus (the adopted grandson of Scipio Africanus, who had wrested Spain away from Carthage in the Second Punic War some seventy years before) destroyed the stronghold at Numancia (Numantia) after an eight-month siege.
Rome had wrested Spain away from Carthage at the Battle of Ilipa in 206 BC (which was won by Scipio Africanus, who would end the Second Punic War four years later at the Battle of Zama) and set about consolidating its control over the native tribes.
In 153 BC, rebellion broke out again. The city of Segeda rebelled, and many Spanish cities joined them. They began building a wall around their city. Nobilior was sent against them, with 30 000 men. He was ambushed by a skilful Segedan general, Carus, and 6000 Romans were slain. However, Carus was slain in a counterattack. Appian, The Spanish War 45 Loeb Bk 6, chap 12
it later formed the centre of Celtiberian resistance to Rome, withstanding repeated attacks. Finally, Scipio Aemilianus (Numantinus) blockaded it (133 BC) by establishing six miles of continuous ramparts around it. After an eight-month siege, Numantia was reduced by hunger, and the survivors capitulated, its destruction ending all serious resistance to Rome in Celtiberia.
Numantia played a central role in the Celt-Iberian resistance to Roman conquest. Its inhabitants withstood repeated Roman attacks from the time of Cato the Elder's campaign (195 B.C.) until Scipio Aemilianus finally took the city in 133 B.C., after an eight-month blockade, thus completing the conquest of Spain.
Scipio Aemilianus Numantinus154-138 2nd Lusitanian war
153-151 2nd Celtiberian war
143-133 3rd Celtiberian war
References: Dio Cassius: Roman History (Vol II) (1914) translated by Earnest Cary (Loeb Classical Library); Appian: Roman History (Vol I) (1912) translated by Horace White (Loeb Classical Library)
Polybius, xxxv, 4; xxxix;
Florus ii, 15,17,18;
Appian, Punica, 72, 98, 113-131; Hispanica 48-95; Bellica Civica i, 19;
Plutarch, lives of Aemilius Paullus, 22, Tiberius Gracchus, 21;
Cicero, De OratorCassio Dio XXII (Viriathus)