Bible Notes Online - Revelation 6 - ESV
Commentary

v1-8: The four horses, compare Mark 13.7-8, bringing warfare and famine on the earth, the beginning of sorrows. Each one is subject to the Lord, released by the Lord opening the seals (5.5). Their 'mission' was restricted, "do not damage the oil and the wine;" and the fourth horse had power over one-fourth of the earth. Yet, the sorrows delivered are significant.

Although such disasters happen throughout history. John is writing about the growing severity of these events towards the end of history. He also shows God's preservation of His people through all circumstances.

v9-11: "Their fellow-servants and brothers," a reference to believing Jews remaining on the earth; some will be killed before the final end of these events, Matt 24.9-10. There is justice from God. No accusation of unfairness can be made against Him, for He will "judge and avenge."

v12-14: The sixth seal brought an earthquake, but a 'heaven-quake' also.

v15-17: The great men of the earth are helpless before the mighty power of God, and the wrath of the Lamb, which is a fearful thing. The sixth seal brings about the "great day of His wrath," identified elsewhere as the Day of the Lord (Joel 2.31; Zeph 1.14-18).