Issus or Issos (Phoenician: Sissu, Ancient Greek: Ἱσσός or Ἱσσοί) is an ancient settlement on the strategic coastal plain straddling the small Pinarus river (a fast melt-water stream several metres wide) below the navigationally difficult inland mountains towering above to the east in the Turkish Province of Hatay, near the border with Syria. It can be identified with Kinet Höyük in the village of Yeṣilköy near Dörtyol in the Hatay province of Turkey. Excavations on the mound occurred between 1992 and 2012 by Bilkent University. It is most notable for being the place of no less than three decisive ancient or medieval battles each called in their own era the Battle of Issus:
Whether Issus is still present within a modern settlement is hotly debated among researchers. Regardless of which mountain brook was the locus of the battles, the old town was situated close to present-day İskenderun, Turkey, in the Gulf of İskenderun. Today, no town exists on both sides of the Pinarus river, which may or may not have been called Issus.
Although Issus was once considered to have been an episcopal see, there is no evidence to support that idea: Issus is not mentioned in the "Notitiae Episcopatuum" of the Patriarchate of Antioch, to which the Roman province of Cilicia belonged.
A battlefield, battleground, or field of battle is the location of a present or historic battle involving ground warfare. It is commonly understood to be limited to the point of contact between opposing forces, though battles may involve troops covering broad geographic areas. Although the term implies that battles are typically fought in a field – an open stretch of level ground – it applies to any type of terrain on which a battle is fought. The term can also have legal significance, and battlefields have substantial historical and cultural value—the battlefield has been described as "a place where ideals and loyalties are put to the test". Various acts and treaties restrict certain belligerent conduct to an identified battlefield. Other legal regimes promote the preservation of certain battlefields as sites of historic importance.
Modern military theory and doctrine has, with technological advances in warfare, evolved the understanding of a battlefield from one defined by terrain to a more multifaceted perception of all of the factors affecting the conduct of a battle and is conceptualised as the battlespace.