Ptolemy and Seleucus, the satrap of Babylonia, invade the satrapy of Syria. The resulting Battle of Gaza leads to a triumph for Ptolemy and Seleucus over Antigonus' son, Demetrius Poliorcetes ("sieger of cities"), who is captured but immediately released. Seleucus ceases his service to Ptolemy and returns to his former province, Babylonia. This event takes place on October 1 and becomes the starting point of the Seleucid era.
The Romancensor, Appius Claudius Caecus, a patrician, enters office and begins construction of the Appian Way (the Via Appia) between Rome and Capua. He also embarks on a program of political reform, including the distribution of the landless citizens of Rome among the tribes, which at this time constitute basic political units. Appius also admits sons of freedmen into the Roman Senate. He also asserts the right of freed slaves to hold office.
Rome gets its first pure drinking water as engineers complete the first aqueduct into the city, the Aqua Appia.