Revelation 6:4

“And there went out another horse, [that was] red, etc.] Which may be an emblem either of the suffering state of the church, being answerable to the Smyrnaean one, as the purity and power of the Gospel, represented in the former seal, may answer to the Ephesine church; or else of those contentions and divisions occasioned among men through the Gospel, which, though of a peaceable nature, yet, through the corruption and depravity of men, brings not peace, but a sword; or rather of those bloody wars within the period of time signified by this seal, which came as punishments on the enemies of the Gospel: and [power] was given to him that sat thereon; not the Lord Jesus Christ, who is said to…”

“red--the color of blood. The color of the horse in each case answers to the mission of the rider. Compare Mat 10:24-36, "Think not I am come to send peace on earth; I came not to send peace, but a sword." The white horse of Christ's bloodless victories is soon followed, through man's perversion of the Gospel, by the red horse of bloodshed; but this is overruled to the clearing away of the obstacles to Christ's coming kingdom. The patient ox is the emblem of the second living creature who, at the opening of this seal, saith, "Come." The saints amidst judgments on the earth in patience "endure to the end." that they should kill--The Greek is indicative future, "that they may, as they also…”

“And there went out another horse - In this symbol there were, as in the others, several particulars which it is proper to explain in order that we may be able to understand its application. The particular things in the symbol are the following: (a) The horse. See this explained in the notes on Revelation 6:2. (b) The color of the horse: another horse that was red. This symbol cannot be mistaken. As the white horse denoted prosperity, triumph, and happiness, so this would denote carnage, discord, bloodshed. This is clear, not only from the nature of the emblem, but from the explanation immediately added: “And power was given to him that sat thereon to take peace from the earth, and that they…”

“There went forth another horse that was red - A colour suitable to bloodshed. And to him that sat thereon it was given to take peace from the earth - Vespasian, in the year 75, had dedicated a temple to Peace; but after a time we hear little more of peace. All is full of war and bloodshed, chiefly in the western world, where the main business of men seemed to be, to kill one another. To this horseman there was given a great sword; and he had much to do with it; for as soon as Trajan ascended the throne, peace was taken from the earth. Decebalus, king of Dacia, which lies westward from Patmos, put the Romans to no small trouble. The war lasted five years, and consumed abundance of men on both…”

“horse: Rev 12:3, Rev 17:3, Rev 17:6; Zac 1:8, Zac 6:2 power: Rev 13:10; Exo 9:16, Exo 9:17; Isa 37:26, Isa 37:27; Eze 29:18-20; Dan 2:37, Dan 2:38, Dan 5:19; Joh 19:11 and there: Psa 17:13; Isa 10:5, Isa 10:6; Eze 30:24, Eze 30:25 Revelation 6:5”