In traditional Adventist reading of Revelation, the primary focus of Revelation 13 is on the Middle Ages (and the role of the Papacy at that time) and beyond (the rise of the USA to world power). But biblically Revelation 13 is an extension of the end-time war of Rev. 12:17. The dragon goes away to make war, calling up allies from the sea and from the land to assist him. Can the two different perspectives be reconciled or does one have to choose one or the other?
It is true that the actual focus of Revelation 13 is on the final battle of earth’s history; with its fiery deceptions, image of the beast, death decree and mark of the beast (Rev. 13:13-17). But few have noticed the verb tenses in the chapter and their implications for its meaning. The main sentences of Revelation 13:1-7, 11 are all in past tenses, mostly aorist indicative in the Greek. On the other hand, the main sentences of Revelation 13:10, 12-18 are all present or future tenses. So the chapter itself clearly contains evidence for sequences of history. Each of the two new beasts acts in the context of the end-time (Rev. 12:17), but has an introduction in past tenses which includes a visual description followed by a summary of its previous history (sea beast: 13:1-7, land beast: 13:11). So the description of the final battle in this chapter (13:12-18) is preceded by the previous history of the two main characters in that battle.
Revelation 13, then, covers two of the historical periods listed in Revelation 12. The introductory, past-tense sections of Revelation 13 (verses 1-7, 11) parallel the middle period of Revelation 12 (12:13-16). The present and future-tense sections of Revelation 13 (verses 8-10, 12-18) parallel the final period of Revelation 12:17. So Revelation 12:17 sets the time of Revelation 13 as a whole, but Revelation 13 includes historical introductions which fit the traditional Adventist perspective. Everything that Uriah Smith and others put into the Middle Ages is in past tense in Revelation 13. Everything that they put into the future is in present or future tenses. To the grammar of the Greek in Revelation 13 supports a historicist reading of the chapter.