2nd Seal - The Red Horse
From the rider on the white horse's actions we are plunged into war.
Red = Bloody power and violence. The word is purrhos in Greek which means fiery, red.
Background Reading:
Revelation 6:3-4
The Second seal, The Red Horse
3 When the Lamb opened the second seal, I heard the second living creature say, "Come!" 4 Then another horse came out, a fiery red one. Its rider was given power to take peace from the earth and to make men slay each other. To him was given a large sword.