Quoting from this article, which I recommend you read in full...
2 Kings 6:17 And Elisha prayed, and said, LORD, I pray thee, open his eyes, that he may see. And the LORD opened the eyes of the young man; and he saw: and, behold, the mountain was full of horses and chariots of fire round about Elisha.
and in 'battle'....
Judges 1:19 And the Lord was with Judah; and he drave out the inhabitants of the mountain; but could not drive out the inhabitants of the valley, because they had chariots of iron.
Yahweh was a god of war...
Psalm 7:13 He has prepared his deadly weapons; he makes ready his flaming arrows.
Psalm 45:5 Let your sharp arrows pierce the hearts of the king's enemies; let the nations fall beneath your feet.
Habakkuk 3:11 Sun and moon stood still in the heavens at the glint of your flying arrows, at the lightning of your flashing spear.
Zachariah 9:14 Then the LORD will appear over them; his arrow will flash like lightning. The Sovereign LORD will sound the trumpet; he will march in the storms of the south.
I believe battles were either conducted solely by the Hebrews using skills born out of a lack of weaponry (cunning, surprise tactics, trickery, man-to-man combat) or by Yahweh (the volcanoes) via volcanic eruptions, ash emissions, lava rivers, rumblings of thunder, lightening, hail storms, etc. The latter the Hebrews were not only accustomed to but also in favour of in enemy territory as they believed these signs and wonders were on their side. Some battles in the Bible may not have been battles at all but territorial and wealth opportunities born out of natural disasters that laid cities to waste allowing the Hebrews to go in afterwards to loot and then claim victory thanks to Yahweh. One example of this could be Jericho, which I believe was destroyed not by Joshua's trumpets but by an earthquake, which was seen as a volcano's 'outstretched arm'.