When He opened the second seal, I heard the second living creature saying, “Come and see.” Another horse, fiery red, went out. And it was granted to the one who sat on it to take peace from the earth, and that people should kill one another, and there was given to him a great sword. (Rev 6:3-4 NKJ)
Seal number two talks about power. Every entity, like the Roman, Babylonia, Assyrian, Persian or even the United States of America is given power, and that power comes from God. It is not uncommon that when a major power falls, like the old Yugoslavia, that smaller powers try to gain more power and will war against each other. Remember, what we see in flesh and blood is only a manifestation of the spiritual realm.
Even the average Christian has power given by God. John tells us, but as many as did receive him to them he gave authority to become sons of God — to those believing in his name, (Joh 1:12 YLT) When you link this to the power to witness (Acts 1:8), the Christian is a dynamic force for good in the world.