John Calvin on Leviticus 26:25

25. And I will bring a sword upon you. There is no doubt but that He means the hostile swords of all the nations, whereby the Israelites were sorely afflicted; and teaches that whosoever should bring trouble and perplexity upon them were the just executioners of His vengeance; just as He constantly declares by the prophets that He was the Leader of the people’s enemies, and that the Assyrians and Chaldeans both fought under Him. He calls the Assyrian His axe, and the rod of His anger which He wields in His hand, (Isaiah 10:15, and 5;) and Nebuchadnezzar His hired soldier. He says that He will call the Egyptians with a hiss, and will arouse the Chaldeans by the sound of his trumpet. (Isaiah 7:20, 18, and elsewhere.) But since this point is sufficiently well known, there will be no occasion of further proofs. The sum is, that all wars are stirred by His command, and that the soldiers are armed at His will, and are strong in His strength. Hence it follows that He has innumerable forces by whose hand He may execute His vengeance whensoever He pleases. Afterwards, therefore, when the Israelites were harassed, and even cruelly oppressed by their enemies, God’s truth was manifested in all those continual defeats; whilst, from His great severity, we may gather how gross was the perversity of their conduct.