Antiochus XII reinforced his southern frontier and warred with his neighbors, conducting two campaigns against Nabataea that included engagements with Judea.

[note 4][22] Antiochus XII was depicted on coinage with an exaggerated hawked nose in the likeness of his father, as a means of strengthening the legitimacy of his succession.

[note 6][36] Gadara held great strategic importance for Syria as it served as a major military hub for operations in the south.

In the view of historian Kay Ehling [de], the change of coin imagery from Atargatis to Hadad probably served two goals: to imply that Antiochus XII had a different policy focus than his predecessor, and to demonstrate his intention of maintaining a good relationship with the Semitic population of Damascus, who comprised the majority of the inhabitants, to avoid tension with Greek settlers.

[24] Seleucid kings presented themselves as protectors of Hellenism and patronized intellectuals and philosophers, but Antiochus XII may have adopted a different attitude; he ordered the expulsion of such scholars.

[53] Antiochus XII's first Nabataean campaign was launched in 87 BC,[54] and might have included a battle near Motho, modern Imtan in the region of Hauran, as proposed by the historian Hans Peter Roschinski, who drew on the writings of Stephanus of Byzantium.

[51] Taking advantage of his brother's absence, Philip I seized Damascus,[59] aided by the governor of the city's citadel, Milesius, who opened the gates to him.

The general closed the gates, locking Philip I out, and awaited the return of Antiochus XII, who had hastily ended his campaign when he heard of his brother's occupation of the city.

This is possibly related to Philip I's attack on Damascus, but this supposition has little support, as Antiochus XII failed to take any action against his brother.

[64] According to Josephus, the Judaean King feared Antiochus XII's intentions and ordered the "Yannai Line" to be built, which consisted of a trench that fronted a defensive wall dotted with wooden towers.

[68] The final engagement between the forces of Antiochus XII and the Nabataeans occurred near the village of Cana,[note 13][71] the location of which is unknown, but is generally assumed by modern scholars to be southwest of the Dead Sea.

[51] Historian Siegfried Mittmann considered it to be synonymous with Qina, modern-day Horvat Uza, as mentioned by Josephus in Book 15 of his Antiquities.

[72] Details of the battle, as written by Josephus, spoke of the Nabataeans employing a feigned retreat,[73] then counterattacking the Syrian forces before their ranks could be ordered.

Antiochus XII managed to rally his troops and weathered the attack, but he fought in the front lines, jeopardizing his life, and he eventually fell.

Fearing the Ituraean ruler Ptolemy, the people of Damascus invited Aretas III of Nabataea to take the city.

[note 14][54] The numismatist Oliver D. Hoover suggested that Aretas III did not hold Damascus for long before the city returned to Seleucid possession.

[76] The identity of Antiochus XII's wife remains unknown,[77] but according to the sixth-century historian John Malalas, whose work is considered generally unreliable by scholars,[78] the King had two daughters, Cleopatra and Antiochis.