The first 80 years, slightly revised but by no means complete
179 BC: Roman dominion in Iberia suffers a serious setback when Praetor Lucius Postumius Albinus is defeated by Lusitani tribes. Propraetor Tiberius Sempronius Gracchus is ambushed and killed by Iberian rebels as he rushes to fight the Lusitani. Wars in Iberia continue.
Phillip V of Macedon dies and is succeeded by Perseus.
Marcus Aemilius Lepidus becomes both censor and princeps senatus.
Emmenes II of Pergamum defeats Pharnaces I of Pontus
178 BC:
Lucius Aemilius Paullus is named Proconsul of Iberia, and defeats the Lusitani, annexing their territory to Rome.
177 BC:
Romans conquer Istria.
176 BC:
Ptolemy VI becomes sole ruler of Egypt
Phraates I becomes King of Parthia
171 BC: Rome declares war on Macedon in 171 BC, at the behest of Pergamum. King Perseus defeats a Roman army led by the consul Publius Licinius Crassus in the battle of Callicinus
168 BC: L. Aemilius Paullus is elected consul again and defeats Macedonians at Pydna. Macedonians surrender, and Illyria, Macedon, and Epirus pass into the Roman orbit.
167 B.C.: Maccabeus revolt of Judea against Seleucids. Judea becomes independent by 160.
150 BC: Cato does not head the commission [butterflied away by conditions in Iberia] mediating between Carthage and the Numidians. Recognizing that further Numidian attacks will force Carthage into armed response Scipio Aemilianus makes a judgment somewhat in Carthage's favor. [how does the noble Censor react?] While the Numidians are furious, Carthage's politics makes a notable swing, with many powerful Carthaginians in favor of trade and association with Rome (the "Roman" party) in opposition to anti-Roman groups (the "Barcids")
[Rebellion fails to break out in Iberia.]
148 BC: Q. Caecilius Metellus defeats the pretender Andriscus of Macedon. War with Achaean league.
147 BC: Scipio Aemilianus becomes Consul
146 BC: Forces under Q. Caecilius Metellus sack Corinth. Greece and Macedon annexed by Rome.
144 BC: Massinissa of Numidia dies, and his three sons unite to attack Carthage. A Roman army under Scipio Aemilianus swiftly conquers Numidia with the aid of Carthaginian auxiliaries and adds Numidia and Tripolitania to the Roman Republic as provinces. Scipio assumes the name "Scipio Numidianus" and later becomes Proconsul of Africa, with responsibility over all Rome's North African posessions as well as being a special emissary to Carthage.
142 BC: To head off Iberian revolt, the Lusitanian chieftain Viriathus is made a special Roman ally. In spite of this, the Celtiberians and certain other Iberian tribes revolt. Viriathus and his Lusitanians destroy Numantia alongside Caepio, who rewards his ally by allowing him to join in the triumph. Viriathus and several other loyal Iberian chieftains are given Roman citizenship.
142 BCE First Stone Bridge with Arches The Pons Aemilius bridge, first bridge to use stone arches, was built across the Tiber River.
140 BC: The Carthaginian factional struggle comes to a head as the “Roman” party attempts to ban human sacrifices to Melqart. While the republic comes to the brink of civil war and the Roman Republic watches greedily, Hasdrubal, a leading member of the Barcid party, leads 5000 Carthaginians away from the city and founds Byrsa on OTL James Island at the mouth of the Gambia, far from any possible Roman influence. The Roman party takes firm control of Carthage and signs a treaty making Carthage’s foreign affairs and military largely subordinate to the Proconsul of Africa.
134 BC: Scattered Iberian revolts continue. Scipio Numidianus is named Proconsul of Iberia.
133 BC: King Attalus III of Pergamum grants his kingdom to Rome after his death.
132 BC: Sicilian slave revolt suppressed brutally by Fulvius Flacchus. Iberia officially declared pacified, and Scipio returns to Rome, where he is declared Princeps Senatus.
131 BC: Scipio observes the depopulation of the Roman countryside due to the reduction in the Roman landowning class after the Punic, Macedonian, and Iberian wars and the corresponding expansion of slave-based megafarms owned by nobles and growth of dispossessed in the cities. In conjunction with the emerging populares faction [TTL without the leadership of Tiberius Sempronius Gracchus, who has been butterflied away] and Appius Claudius Pulcher, he proposes a series of military and social reforms to restore the virtues of "old Rome."
The first step was allocating the vast tracts of public land which had come into Roman hands according to traditional Roman laws, with limits to the amount of property. Compared to Gracchus, Pulcher's party plays politics better and the ultra-rich nobles do not raise a fuss.
Military reform then proposed by Scipio. Every Roman tribus and Italian socius are expected to provide a certain number of cohorts, which generally include all men of landowning class* from 18-24. These cohorts are age-based, like the Zulu impis, and rotate every six years, though expired cohorts can be kept in service on the authority of anyone holding imperium. The intent is that young men will serve the Republic, and their families will continue to hold their land. Older and younger cohorts would serve as an organized reserve and drill yearly under the direction of [tribal officers]. This measure met with more opposition, but was recognized as a wise measure in light of the Republic’s growing manpower needs and the dangers of a permanent army, and was also adopted completely by 120 B.C. Eventually, this concept will apply to new socii outside Italy.
*Cavalry alae would also be provided by equestrians
125 B.C.: Fulvius Flacchus moves that Italian citizenship be extended to all Italians, and their tribes be placed equal to Roman tribes. Flacchus is sent away to assist Roman ally Massalia by opponents of the measure.
125 B.C.: New Roman territory in Iberia, Africa, and Illyria is opened to Pulcher's land reforms. Roman colonies emerge among troublesome tribes. A proposed measure to subsidize grain for the city of Rome is NOT approved; the moderate faction prefers to encourage Roman settlement in new territories, despite the reluctance of many to leave Italy. Roman citizenship is also offered to any Italian who settles in these new territories, reducing tension among Rome's allies.
Major public works projects are launched in Italy, to the benefit of the equestrian class. Populares and optimates factions within the Senate and other public assemblies continue cooperation for the benefit of Rome. The political climate generally opposes the expansion of noble privilege without curtailing existing privilege.
Scipio Numidianus named Censor.
121 B.C. Due to the conquests of Fulvius Flacchus, Transalpine Gaul becomes a Roman province.
118 B.C.: Jugartha, a Numidian nobleman, starts a revolt in the Numidian hinterland. Carthage is allowed to mobilize and sends auxiliaries, but still Lucius Calpurnius Bestia's forces fail to make headway against Numidian light horse. The war is inconclusive for 9 years.
115 B.C.: Byrsa expands its trade network, placing settlements up the Atlantic coast of Africa to the Pillars of Hercules, but avoiding any entanglement with Roman affairs in Mediterranean Africa and Iberia. Trading posts are set up along the Gambia River and around the curve of Africa, triggering development of states in these regions.
109 B.C.: Rumors of corruption among Roman officials in Numidia result in a purge in the province. Quintus Metellus takes command against Jugartha. Among the government reforms, Carthage is officially made a Roman client. Jugartha is decisively beaten and driven into refuge in Mauretania.
109 B.C.: Teutones and Cimbri defeat Roman consul Silanus in Gaul.
108 B.C.: Metellus invades Mauretania, decisively defeating the Numidian and Mauretanian armies and capturing Jugartha and Mauretanian king Bocchus. Mauretania is annexed to Rome and Metellus is made proconsul of an expanded Africa. Numidian tribes continue rebellion for years to come, and Africa becomes the proving ground for generations of Roman cohorts stationed there. Carthage never disarms after the rebellion, but its army and navy have become mere adjuncts to the forces of the Roman Proconsul. Alae of light horsemen from the allied Numidian tribes become a common feature of Roman armies around the world.
107 B.C.: Helvetians defeat the army of the consul Cassius.
105 B.C.: Gaius Marius is named consul. Inactive cohorts are recalled to duty, and Marius forms the first permanent cohorts from among the urban poor and Italian allies, equipped at public expense. A Roman army of 100,000 meets the Teutones, Cimbri, and Helvetii at Arausio, destroying those tribes' power and driving them beyond the Alps. Marius and his successor Catullus continue the reforms set in place by Scipio and Pulcher. Now, ten years' service in the permanent cohorts equipped by the Senate is required for Roman and Italian dispossessed to be placed in coloni. Legions are formed in all the outlying provinces of Rome, consisting (at first) of 6 tribal cohorts and 2 Senatorial cohorts, under the command of the provincial legate. The proconsulship in pacified Iberia is abolished and replaced by one in Gaul, which Marius assumes after Catullus takes the consulship.
*Marius may not have as much political capital in ATL, due to his lesser role in the Jugarthine rebellion.
103 B.C.: The consul Catullus stamps out a second Sicilian slave revolt, though parts of the island remain in rebellion for the next three years. A promising young military officer called Lucius Cornelius Sulla is assassinated* in his tent by Sicilan rebels, for which Catullus exacts gruesome revenge.
*I don’t really see how I can keep Sulla alive without serious disruption to the Republic.
100 B.C.: Marius, Proconsul of Gaul, forges a network of alliances with tribes across the southern half of Gaul, laying plans for eventual conquest. These plans are interrupted when Helvetii pour out of the Alps in force again, accompanied by various German and Celtic tribes, including the remnants of the Teutones and the Cimbri. In a series of brilliant campaigns, Marius’ legions, along with many Gaulish auxiliaries, destroy the invading tribes. In a move that foreshadows Rome’s foreign policy for years to come, small pockets of Teutones and Helvetii are scattered through Rome’s possessions (mainly Iberia, in this case) and their place taken by a mix of friendly tribes and Roman coloni.
Western Raetia and Aquitania are annexed to Rome in the wake of these victories, and again foreshadowing Rome’s imperial policy, leading families of friendly tribes are given Roman citizenship.
98 B.C.: Marius returns to Rome triumphantly, taking office as Consul again. Illyria is formally annexed as a Roman province, and Pannonia and Noricum become Roman client kingdoms.
97 B.C.: Quintus Sertorius conquers Iberian holdouts and embarks on extensive Romanization program within the peninsula. Iberian tribal groups are broken up and scattered throughout the Republic, their place taken by a mix of voluntary and involuntary migrants from all over.
95 B.C.: Gaulish Parisii tribe expands to cover most of Rome’s northern border, supported by the Romans in Transalpine and Aquitinian Gaul. Nucleic Belgic, Armoric, and Suebii confederacies form in response.
91 B.C.: Tribune Livius Drusus revives the proposal to extend Roman citizenship to Italian socii. Due to the demand for tribal cohorts to check the threat of military takeover by the permanent cohorts (the ratio is intended to be 3 to 1, which will not change for some time), the proposal passes almost with little opposition. The socii tribes hold the same legal status and duties as the old Roman tribes, though do not [yet] receive Senate membership alongside Roman nobiles.*
*Yes, this will change, very soon.