Albert Barnes Commentary Revelation 6:15

"And the kings of the earth, and the princes, and the chief captains, and the rich, and the strong, and every bondman and freeman, hid themselves in the caves and in the rocks of the mountains;" — Revelation 6:15 (ASV)

The universal consternation: And the kings of the earth, and others. The design of this and the following verses (Revelation 6:15–17), in the varied language used, is evidently to denote universal consternation and alarm—as if the earth should be convulsed, the stars should fall, and the heavens should pass away. This consternation would extend to all classes of men, and fill the world with alarm, as if the end of all things were coming.

The kings of the earth: These are rulers—all who occupied thrones.

The great men: These are high officers of state.

And the rich men: Their wealth would not secure them from destruction, and they would be alarmed like others.

And the chief captains: These are the commanders of armies, who tremble like other men when God appears in judgment.

And the mighty men: These are men of great prowess in battle, but who now feel that they have no power to withstand God.

And every bondman: This refers to a servant—Greek, doulos. This word does not necessarily denote a slave (see 1 Timothy 6:1; 1 Timothy 1:16), but here the connection seems to demand it, as it stands in contrast with freeman. Indeed, there were slaves in the Roman Empire, and there is no objection to supposing that they are referred to here. There is no reason why they should not be filled with consternation as well as others; and as this passage does not refer to the end of the world or the day of judgment, the word here determines nothing about whether slavery is to continue on the earth.

And every freeman: This includes whether one was the master of slaves or not. The idea is that all classes of men, high and low, would be filled with alarm.

Hid themselves in the dens: This means among the caves or caverns in the mountains . These places were resorted to for safety in times of danger (compare 1 Samuel 13:6; 1 Samuel 24; Judges 6:2; Jeremiah 41:9; also Josephus, Antiquities, Book XIV, Chapter 15, and Jewish Wars, Book I, Chapter 16).

And in the rocks of the mountains: This refers to being among the crags or the fastnesses of the mountains—also natural places of refuge in times of hostile invasion or danger .

See also Revelation 6:16 and following.