The Bible says that Nimrod "went forth into Assyria," which was evidently an act of aggression, into the territory of Asshur the son of Shem. There Nimrod built cities.
(Ge 10:11) In Abraham’s day Chedorlaomer, king of Elam, subjected a number of cities (all apparently around the southern end of the Dead Sea) for a period of 12 years, forcing them to serve him. After they rebelled, Chedorlaomer and his allies warred against them, vanquishing the forces of Sodom and Gomorrah, taking their possessions, and capturing Abraham’s nephew Lot and his household. At that Abraham mustered 318 trained servants and, together with his three confederates, pursued Chedorlaomer and recovered the captives and the plunder. However, Abraham did not take any of the booty for himself. This is the first record of a war waged by a servant of God. Abraham’s warring to recover his fellow servant of Jehovah had Jehovah’s approval, for, on Abraham’s return, he was blessed by Melchizedek, priest of the Most High God.—Ge 14:1-24.
Warfare. Jehovah is "a manly person of war," "the God of armies," and "mighty in battle." (Ex 15:3; 2Sa 5:10; Ps 24:8, 10; Isa 42:13) Not only has he the right as Creator and Supreme Sovereign of the universe but he is also obligated by justice to execute or authorize execution of the lawless, to war against all obstinate ones who refuse to obey his righteous laws. Jehovah was therefore just in wiping out the wicked at the time of the Flood, in destroying Sodom and Gomorrah, and in bringing destruction upon Pharaoh’s forces.—Ge 6:5-7, 13, 17; 19:24; Ex 15:4, 5; compare 2Pe 2:5-10; Jude 7.
used as God’s executioner. Jehovah assigned the Israelites the sacred duty of serving as his executioners in the Promised Land to which he brought them. Prior to Israel’s deliverance from Egypt, the nation had not known warfare. (Ex 13:17) By victoriously directing Israel against "seven nations more populous and mighty" than they were, God magnified his name as "Jehovah of armies, the God of the battle lines of Israel." This proved that "neither with sword nor with spear does Jehovah save, because to Jehovah belongs the battle." (De 7:1; 1Sa 17:45, 47; compare 2Ch 13:12.) It also gave the Israelites the opportunity to demonstrate obedience to God’s commandments to the point of endangering their lives in God-ordained warfare.—De 20:1-4.
aggression beyond the God-given limits. However, God strictly commanded Israel that they were not to engage in wars of aggression or conquest beyond the territory that he granted to them and that they were not to fight any nations except the ones he ordered them to fight. They were not to engage in strife with the nations of Edom, Moab, or Ammon. (De 2:4, 5, 9, 19) But they were attacked by these nations in later times and were forced to defend themselves against them in warfare. In this they had God’s help.—Jg 3:12-30; 11:32, 33; 1Sa 14:47.
When, during the period of the Judges, the king of Ammon tried to justify his aggressions against Israel by falsely charging Israel with taking Ammonite land, Jephthah refuted him by recalling the historical facts. Jephthah then proceeded to fight against these aggressors, on the principle that ‘every one whom Jehovah dispossesses before us we will dispossess.’ Jephthah would not relinquish an inch of Israel’s God-given land to any intruder.—Jg 11:12-27;
warfare. Anciently, the fighting forces, before they entered battle, were customarily sanctified. (Jos 3:5; Jer 6:4; 51:27, 28) During warfare Israel’s forces, including non-Jews (for example, Uriah the Hittite, who was probably a circumcised proselyte), had to remain ceremonially clean. They could not have sexual relations, even with their own wives, during a military campaign. Accordingly, there were no prostitutes who followed Israel’s army. Moreover, the camp itself had to be kept clean from defilement.—Le 15:16, 18; De 23:9-14; 2Sa 11:11, 13.
When it was necessary to punish unfaithful Israel, those foreign armies bringing the destruction were viewed as ‘sanctified,’ in the sense that they were ‘set apart’ by Jehovah for the execution of his righteous judgments. (Jer 22:6-9; Hab 1:6) Similarly, those military forces (principally the Medes and Persians) who brought destruction on Babylon were spoken of by Jehovah as "my sanctified ones."—Isa 13:1-3.
The false prophets in Israel, in their greediness, were said to "sanctify war" against anyone who did not put something into their mouths. Undoubtedly they sanctimoniously claimed divine sanction for their acts of oppression, which included sharing in the responsibility for the persecution and even the death of true prophets and servants of God.—Mic 3:5; Jer 2:8; La 4:13.