And they had breastplates, as it were breastplates of iron; and the sound of their wings was as the sound of chariots of many horses running to battle.

And they had breastplates as breastplates of iron, and the noise of their wings was as the noise of chariots and many horses running to battle.

and they had breastplates as breastplates of iron, and the sound of their wings was as the sound of chariots of many horses running to war;

And they had breast-plates, as it were breast-plates of iron; and the sound of their wings was as the sound of chariots of many horses running to battle.

They had breast-plates which seemed to be made of steel; and the noise caused by their wings was like that of a vast number of horses and chariots hurrying into battle.

And they had breastplates like iron, and the sound of their wings was as the sound of carriages, like an army of horses rushing to the fight.

And they had breastplates like iron breastplates. And the noise of their wings was like the noise of many running horses, rushing to battle.

and they had what seemed to be iron breastplates, while the noise of their wings was like the noise of chariots drawn by many horses, galloping into battle.

And they had breastplates, as it were breastplates of iron - Hard, horny, impenetrable, as if they were made of iron. The locust has a firm and hard cuticle on the forepart of the breast, which serves for a shield or defense while it moves in the thorny and furzy vegetation. On those which John saw this was especially hard and horny, and would thus be well adapted to be an emblem of the breastplates of iron commonly worn by ancient warriors. The meaning is, that the warriors referred to would be well clad with defensive armor.
And the sound of their wings was as the sound of chariots of many horses running to battle - The noise made by locusts is often spoken of by travelers, and the comparison of that noise with that of chariots rushing to battle, is not only appropriate, but also indicates clearly what was symbolized. It was an army that was symbolized, and everything about them served to represent hosts of men well armed, rushing to conflict. The same thing here referred to is noticed by Joel Joel 2:4-5, Joel 2:7;
"The appearance of them is as the appearance of horses;
And as horsemen so shall they run.
Like the noise of chariots on the tops of mountains, shall they leap;
Like the noise of a flame of fire that devoureth the stubble;
As a strong people set in battle array.
They shall run like mighty men;
They shall climb the wall like men of war;
And they shall march every one his ways,
And shall not break their ranks," etc.
It is remarkable that Volney, who had no intention of illustrating the truth of Scripture, has given a description of locusts, as if he meant to confirm the truth of what is here said. "Syria," says he, "as well as Egypt, Persia, and almost all the south of Asia, is subject to another calamity no less dreadful (than earthquakes); I mean those clouds of locusts so often mentioned by travelers. The quantity of these insects is incredible to all who have not themselves witnessed their astounding numbers; the whole earth is covered with them for the space of several leagues. The noise they make in browsing on the trees and herbage may be heard to a great distance, and resembles that of an army foraging in secret" (Travels in Egypt and Syria, vol. i. pp. 283, 284).

They had breastplates - of iron - They seemed to be invulnerable, for no force availed against them.
The sound of their wings - Their hanging weapons and military trappings, with the clang of their shields and swords when they make their fierce onsets. This simile is borrowed from Joel 2:5-7.

And they had breastplates, as it were breastplates of iron,.... Alluding to the hard skin of the locusts, with which nature has fenced it (q); see Joel 2:8; and denotes the armour with which the Saracens were accoutred: and if to be understood of the western locusts, the hardness of their hearts, their seared consciences, or their protection by the princes of the earth, the many privileges they are possessed of, the laws made in their favour, and for their security; their breastplates were not breastplates of righteousness, faith, and love, nor in defence of truth, but against it. And some think the iron colour may denote the colour of their habit, their black garments:
and the sound of their wings was as the sound of chariots of many horses running to battle; see Joel 2:5. The sound of locusts, when they fly or march in large companies, is very great. Pliny says (r), they make such a noise with their wings, when they fly, that they have been thought to have been other winged creatures; hence a locust, in Hebrew, is sometimes called the same name that is given to the high sounding cymbal. The sound of them is said to have been heard six miles (s). Aristotle (t) ascribes it to the rubbing of their legs or thighs one against another; and so the Ethiopic version here renders it, "the sound of their feet": this may be expressive of the swift and rapid incursions of the Saracens, and of the dreadful alarms to the nations which their invasions made; and may be applied to the noisy declamations, anathemas, excommunications, and interdicts of the Romish clergy.
(q) Claudian. Epigram. 13. (r) Plin. l. 11. c. 29, 51. (s) Altissiodorensis in Joel ii. 5. (t) Hist. Animal. l. 4. c. 9. Vid. Plin. l. 11. c. 51.

as it were breastplates of iron--not such as forms the thorax of the natural locust.
as . . . chariots-- (Joel 2:5-7).
battle--Greek, "war."

And the noise of their wings was as the noise of chariots of many horses - With their war - chariots, drawn by many horses, they, as it were, flew to and fro.