Revelation 12 describes War in Heaven in which Satan, the “Dragon”, is cast out of Heaven. This is actually a continuation of the Great Controversy which began when Satan challenged God and accused Him of being unjust. Sin entered this world when Adam and Eve accepted Satan’s accusations.
The Seven Trumpets of Revelation depict a great war that takes place at the end of time, which is a part of the Great Time of Trouble. This war takes place while the 144,000 are giving God’s last message to the world and are Satan’s attempt to stop them.