Thapsus (less commonly, Tapsus) was an ancient city in what is modern day Tunisia. Its ruins exist at Ras Dimas near Bekalta, approximately 200 km southeast of Carthage. Originally founded by Phoenicians, it served as a marketplace on the coast of the province Byzacena in Africa Propria. Thapsus was established near a salt lake on a point of land eighty stadia (14.8 km) from the island of Lampedusa.

In 46 BC, Julius Caesar defeated Metellus Scipio and the Numidian King Juba with a tremendous loss of men near Thapsus (see Battle of Thapsus). Caesar exacted a payment of 50,000 sesterces from the vanquished. Their defeat marked the end of opposition to Caesar in Africa. Thapsus then became a Roman colony.

Coordinates: 35°37′33″N 11°02′42″E / 35.62583°N 11.045°E / 35.62583; 11.045

Gaius Julius Caesar (Classical Latin: [ˈɡaː.i.ʊs ˈjuː.lɪ.ʊs ˈkaj.sar], July 100 BC – 15 March 44 BC) was a Roman general and statesman and a distinguished writer of Latin prose. He played a critical role in the gradual transformation of the Roman Republic into the Roman Empire.

In 60 BC, Caesar, Crassus and Pompey formed a political alliance that was to dominate Roman politics for several years. Their attempts to amass power through populist tactics were opposed by the conservative elite within the Roman Senate^{[citation needed]}, among them Cato the Younger with the frequent support of Cicero. Caesar's conquest of Gaul, completed by 51 BC, extended Rome's territory to the English Channel and the Rhine. Caesar became the first Roman general to cross both when he built a bridge across the Rhine and conducted the first invasion of Britain.

These achievements granted him unmatched military power and threatened to eclipse Pompey's standing. The balance of power was further upset by the death of Crassus in 53 BC. Political realignments in Rome finally led to a standoff between Caesar and Pompey, the latter having taken up the cause of the Senate. Ordered by the Senate to stand trial in Rome for various charges, Caesar marched on Rome with one legion—legio XIII—from Gaul to Italy, crossing the Rubicon in 49 BC. This sparked a civil war from which he emerged as the unrivaled leader of the Roman world.