Final answer:
The Roman Republic gained control of parts of northern Africa through their victory in the Punic Wars, which concluded in 146 BCE with the defeat of Carthage, making North Africa a vital part of the Roman Empire.
Step-by-step explanation:
The event that allowed the Roman Republic to control parts of northern Africa was the series of conflicts known as the Punic Wars against Carthage. The first Punic War began in 264 BCE, and by the end of the third Punic War in 146 BCE, Rome had defeated Carthage and gained control of its territories, which included parts of North Africa. The victory in these wars enabled Rome to expand its territory significantly, cementing its power across the Mediterranean region. To solidify its control, Rome integrated local economies and infrastructure, building roads, aqueducts, and port facilities, actions that later facilitated the movement of goods such as grain and olive oil from these regions, earning North Africa the nickname 'the breadbasket of Rome.'