As the first angel sounded his trumpet, John saw “hail and fire mingled with blood” and they were cast upon the earth (Revelation 8:7). By earth the Scripture means the land of the Jews—Judea and Galilee (and perhaps Samaria). So, the judgments are largely confined to this area. Therefore, the Apocalypse could not be speaking of the whole world, but, rather, it concerns itself with a specific area within the Roman Empire (viz. Revelation 16:2, 10, 12) and a specific period of time.
In a previous study I showed how the ancient rabbis concluded that the days of the Messiah would last 40 years, concerning which I concluded that those years fell between 31 AD to 70 AD. This period of time would incorporate the opening of the seals to about 54-56 AD, and the time of Paul’s imprisonment. From this time forward to the beginning of the Jew’s war with Rome in 66 AD, would incorporate the time of the blowing of the seven trumpets. If this is logical and accurate, the “hail and fire mingled with blood” was cast into the lands of Judea and Galilee, but its full effect would also be felt in the Diaspora. Nevertheless, can such a thing be proved?
The first thing we need to understand is the Greek in Revelation 8:7 is translated poorly, at least in one respect. It should, rather, reflect the plague Moses called down upon Egypt (Exodus 9:23-25), hail mingled with fire, and their mixture is in blood. That is, one doesn’t see the “hail and the fire” per se, but one does see the blood. It is a judgment sent down from God against the unbelieving Jewish nation, which is identified as spiritual Egypt in the Apocalypse (cf. Revelation 11:8). Notice how the Pulpit Commentary puts it:
“The English Version is ambiguous, but the Greek makes it clear that it is the hail and the fire that are mingled, and that both together are sent in blood.” [Pulpit Commentary]
Yet, even with this correction, the judgment still doesn’t make a lot of sense. What does it mean to say “the fire and the hail are not mingled ‘with’ blood?” They are mingled ‘in’ blood! It is interesting that Isaiah compares a hail storm with the coming of the Assyrian king against Samaria in Isaiah 28:1-2. The hail storm casts **it** (i.e. Samaria) down to the earth, because they are overcome with wine and pride (verse-1). Isaiah continues in his prophecy to say:
Isaiah 28:16 Therefore thus says the Lord GOD, Behold, I lay in Zion for a foundation a stone, a tried stone, a precious corner stone, a sure foundation: he that believes shall not make haste.
Thus, we have the judgment of hail stones in Isaiah 28:2 (cf. Joshua 10:11) in the light of laying a Foundation Stone in Zion, but he who believes on him will not be ashamed (Septuagint and Romans 9:33). In the context of Revelation 8:7 this could be understood as the Lord sending to the Jewish nation hailstones in the form of “prophets and wise men and scribes” (Matthew 23:34; stones 1Peter 2:5). In other words the Lord rained down the apostles and evangelists etc. upon the Jewish nation, having a message of fire (cf. Jeremiah 23:29), which by its nature destroyed the false teaching preached by the Jewish authorities of the first century AD.
James uses the tongue as a symbol for the words one speaks. If one’s words are evil, like a fire, they defile and destroy a lot of good (James 3:6). On the other hand, if one’s words are truth, as though the truth were a fire, they destroy the lie, or false doctrine (Jeremiah 23:29; cf. Job 15:31-35; Isaiah 28:15-18).
Thus, the hail and the fire (Jesus’ disciples preaching the Gospel) were mingled in blood, meaning persecution (Matthew 23:34). For this reason a third part of the trees were burnt up, which is an intensification of the judgment of the seals, where power was given over only a quarter part of the earth (the Jewish lands) “to kill with sword, and with hunger, and with death, and with the beasts of the earth” (cf. Revelation 6:8). A tree is often depicted as a righteous man (Psalm 1:3; Jeremiah 17:8), or a strong king (Daniel 4:10-12), or the great men of a nation (Isaiah 2:13). Judgment had been pronounced against the nation of the Jews, even at the beginning of Jesus’ ministry, in that the axe was laid at the root of the trees (Matthew 3:10), and every tree that didn’t bring forth good fruit would be cut down (Matthew 7:17-19).
As for the grass of the field, the Scripture has determined that it represents the people (Isaiah 40:6-8). The righteous and the unrighteous grew together until the harvest, at which time they are separated and that which was not fruitful was to be discarded and burned up, while the fruitful were protected (Matthew 13:30, 39-42; cf. Revelation 9:4). Thus, the judgment of the First Trumpet is Jesus as the Prophet of God sending his disciples: “prophets and wise men and scribes” (Matthew 23:34), also referred to as hail stones (1Peter 2:5) in the text. It is a kind of spiritual war (cp. Revelation 12:7-11 and Luke 10:1-12, 17-18), a spiritual war of words, truth preached against false doctrine, whereby the false doctrine is burned up in the fire of the truth. The war ends in persecution (blood) of the righteous, but this **war** also continues until the time of the harvest.
 See also Philip Schaff’s Popular Commentary at Revelation 8:7