The three remaining trumpets (fifth, sixth, and seventh trumpets) herald three woes to come (The Three Woes, pg. 65).
“The three remaining trumpets (ch. ix-xi) are usually called the woe-trumpets, in reference to the proclamation of woes, ch. viii. 18…. The three extend… as it is supposed by the writer himself (ch. xi. 15), to the period when ‘the kingdoms of this world shall have become the kingdom of Christ,’ embracing a succinct view of the most material events that were to occur, particularly in a secular point of view.”
Albert Barnes, Notes on … Revelation, p. 239.