Final answer:
Antony married Cleopatra VII, the queen of Egypt, to form an alliance with Egypt and invade Parthia.
Step-by-step explanation:
In order to invade Parthia, Antony formed an alliance with Egypt by marrying Cleopatra VII, the Macedonian queen of Egypt. Cleopatra was already the co-ruler of Egypt with her son Ptolemy XV, who was fathered by Julius Caesar. Antony and Cleopatra's alliance allowed Antony to raise an army and fleet with Cleopatra's financial support.