Masinissa was the son of the chieftain Gaia of a Numidian tribal group, the Massylii.
He was brought up in Carthage, an ally of his father.
At the start of the Second Punic War, Masinissa fought for Carthage against Syphax, the king of the Masaesyli of western Numidia (present day Algeria), who had allied himself with the Romans.
Masinissa, then about 17 years old, led an army of Numidian troops and Carthaginian auxiliaries against Syphax's army and won a decisive victory (215-212 BC).
He was betrothed to the daughter of the Carthaginian general Hasdrubal Gisgo.

After his victory over Syphax, Masinissa commanded his skilled Numidian cavalry against the Romans in Spain, where he was involved in the Carthaginian victories of Castulo and Ilorca in 211 BC.
After Hasdrubal Barca departed for Italy, Masinissa was placed in command of all the Carthaginian cavalry in Spain, where he fought a successful guerrilla campaign against the Roman general Publius Cornelius Scipio (Scipio Africanus) throughout 208 and 207, while Mago Barca and Hasdrubal Gisgo levied and trained new forces.
In c.206 BC, with fresh reinforcements, Mago and Hasdrubal Gisgo—supported by Masinissa's Numidian cavalry—met Scipio at the Battle of Ilipa, where Carthage's power over Hispania was forever broken in arguably Scipio Africanus's most brilliant victory.

When Gaia died in 206 BC, his son Masinissa and his brother Oezalces quarreled about the inheritance, and Syphax was able to conquer considerable parts of eastern Numidia.
Meanwhile, with the Carthaginians having been driven from Hispania, Masinissa concluded that Rome was winning the war against Carthage and therefore decided to defect to Rome.
He promised to assist Scipio in the invasion of Carthaginian territory in Africa.
This decision was aided by the move by Scipio Africanus to free Masinissa's nephew, Massiva, whom the Romans had captured when he had disobeyed his uncle and ridden into battle.
Having lost the alliance with Masinissa, Hasdrubal started to look for another ally, which he found in Syphax, who married Sophonisba, Hasdrubal's daughter, who until the defection had been betrothed to Masinissa.
The Romans supported Masinissa's claim to the Numidian throne against Syphax, who was nevertheless successful in driving Masinissa from power until Scipio invaded Africa in 204.
Masinissa joined the Roman forces and participated in the victorious Battle of the Great Plains (203).

At the Battle of Bagbrades (203), Scipio overcame Hasdrubal and Syphax and, while the Roman general concentrated on Carthage, Gaius Laelius and Masinissa followed Syphax to Cirta, where he was captured and handed over to Scipio.
After the defeat of Syphax, Masinissa married Syphax's wife Sophonisba, but Scipio, suspicious of her loyalty, demanded that she be taken to Rome and appear in the triumphal parade.
To save her from such humiliation, Masinissa sent her poison, with which she killed herself.
Masinissa was now accepted as a loyal ally of Rome, and was confirmed by Scipio as the king of the Massylii.

At the Battle of Zama, Masinissa commanded the cavalry (6,000 Numidian and 3,000 Roman) on Scipio's right wing, Scipio delayed the engagement long enough to allow for Masinissa to join him.
With the battle hanging in the balance, Masinissa's cavalry, having driven the fleeing Carthaginian horsemen away, returned and immediately fell onto the rear of the Carthaginian lines.
This decided the battle and at once Hannibal's army began to collapse.
The Second Punic War was over and for his services Masinissa received the kingdom of Syphax, and became king of Numidia.

Masinissa was now king of both the Massylii and the Masaesyli.
He showed unconditional loyalty to Rome, and his position in Africa was strengthened by a clause in the peace treaty of 201 between Rome and Carthage prohibiting the latter from going to war even in self-defense without Roman permission.
This enabled Masinissa to encroach on the remaining Carthaginian territory as long as he judged that Rome wished to see Carthage further weakened.
Masinissa was the son of the chieftain Gaia of a Numidian tribal group, the Massylii. He was brought up in Carthage, an ally of his father. At the start of the Second Punic War, Masinissa fought for Carthage against Syphax, the king of the Masaesyli of western Numidia (present day Algeria), who had allied himself with the Romans. Masinissa, then about 17 years old, led an army of Numidian troops and Carthaginian auxiliaries against Syphax's army and won a decisive victory (215-212 BC). He was betrothed to the daughter of the Carthaginian general Hasdrubal Gisgo.
After his victory over Syphax, Masinissa commanded his skilled Numidian cavalry against the Romans in Spain, where he was involved in the Carthaginian victories of Castulo and Ilorca in 211 BC. After Hasdrubal Barca departed for Italy, Masinissa was placed in command of all the Carthaginian cavalry in Spain, where he fought a successful guerrilla campaign against the Roman general Publius Cornelius Scipio (Scipio Africanus) throughout 208 and 207, while Mago Barca and Hasdrubal Gisgo levied and trained new forces. In c.206 BC, with fresh reinforcements, Mago and Hasdrubal Gisgo—supported by Masinissa's Numidian cavalry—met Scipio at the Battle of Ilipa, where Carthage's power over Hispania was forever broken in arguably Scipio Africanus's most brilliant victory.
When Gaia died in 206 BC, his son Masinissa and his brother Oezalces quarreled about the inheritance, and Syphax was able to conquer considerable parts of eastern Numidia. Meanwhile, with the Carthaginians having been driven from Hispania, Masinissa concluded that Rome was winning the war against Carthage and therefore decided to defect to Rome. He promised to assist Scipio in the invasion of Carthaginian territory in Africa. This decision was aided by the move by Scipio Africanus to free Masinissa's nephew, Massiva, whom the Romans had captured when he had disobeyed his uncle and ridden into battle. Having lost the alliance with Masinissa, Hasdrubal started to look for another ally, which he found in Syphax, who married Sophonisba, Hasdrubal's daughter, who until the defection had been betrothed to Masinissa. The Romans supported Masinissa's claim to the Numidian throne against Syphax, who was nevertheless successful in driving Masinissa from power until Scipio invaded Africa in 204. Masinissa joined the Roman forces and participated in the victorious Battle of the Great Plains (203).
At the Battle of Bagbrades (203), Scipio overcame Hasdrubal and Syphax and, while the Roman general concentrated on Carthage, Gaius Laelius and Masinissa followed Syphax to Cirta, where he was captured and handed over to Scipio. After the defeat of Syphax, Masinissa married Syphax's wife Sophonisba, but Scipio, suspicious of her loyalty, demanded that she be taken to Rome and appear in the triumphal parade. To save her from such humiliation, Masinissa sent her poison, with which she killed herself. Masinissa was now accepted as a loyal ally of Rome, and was confirmed by Scipio as the king of the Massylii.
At the Battle of Zama, Masinissa commanded the cavalry (6,000 Numidian and 3,000 Roman) on Scipio's right wing, Scipio delayed the engagement long enough to allow for Masinissa to join him. With the battle hanging in the balance, Masinissa's cavalry, having driven the fleeing Carthaginian horsemen away, returned and immediately fell onto the rear of the Carthaginian lines. This decided the battle and at once Hannibal's army began to collapse. The Second Punic War was over and for his services Masinissa received the kingdom of Syphax, and became king of Numidia.
Masinissa was now king of both the Massylii and the Masaesyli. He showed unconditional loyalty to Rome, and his position in Africa was strengthened by a clause in the peace treaty of 201 between Rome and Carthage prohibiting the latter from going to war even in self-defense without Roman permission. This enabled Masinissa to encroach on the remaining Carthaginian territory as long as he judged that Rome wished to see Carthage further weakened.
Masinissa