Polemos (G4171) means war, battle, or armed conflict. Its root gives us 'polemical.' In the New Testament it describes literal wars (Matt 24:6), the heavenly war in Revelation (Rev 12:7), and the spiritual warfare of James 4:1 ('What causes fights and quarrels among you?').
James cuts to the heart of polemos theology in James 4:1: 'What causes wars and what causes fightings among you? Is it not this, that your passions are at war within you?' The external wars of nations trace back to the internal wars of desire. Revelation 12:7-9 reveals a polemos in heaven — Michael and his angels fighting the dragon — won not by military force but 'by the blood of the Lamb and by the word of their testimony' (Rev 12:11). Jesus' warning in Matthew 24:6 — 'you will hear of wars' — includes these among the beginning of birth pains, not the end. The ultimate polemos is the Lamb's war (Rev 17:14) which He wins decisively. 'The Lord of hosts' — YHWH Tsabaoth — is the God of armies who wins the war.