This takes place in time and space but there are also hints of it happening at an unseen level as well. It is interesting that the four times Satan is mentioned in the Old Testament, they have nothing to do with such battles. In the New Testament, as soon as the kingdom of God arrives in the person of Jesus Christ, Satan or the devil or the evil one as he is variously called, counterattacks intermittently. The areas of conflict are Jesus' understanding of himself and his mission, the loyalty of the disciples, notably Peter and Judas, demon possessed people, and the hardness in the religious and political authorities. Satan and his minions are cast out by the cross and resurrection of Jesus.
Conflict is present everywhere but the language of warfare is used only twice.
In Acts, the progress of the gospel is countered from within the church by Ananias who allowed Satan to fill his heart with a lie and externally in the palace, by Elymas, the sorcerer, said to be a son of the devil. Demons and evil spirits are still cast out. Conflict is still present but not the language of warfare. The language of warfare is scattered throughout the book of Revelation but all the initiatives and the victories here are solely originated by God himself. In Paul's letters we have a few references to warfare and armour.