The Tribulation lasts seven years and there are three major wars. World War III is the 6th Trumpet between China, the United States and India (Revelation 9:14-16). World War IV is Gog and Magog when Russia and radical Islam (Iran, Turkey, Libya) attack Israel (Ezekiel 38:2-3, 4-5). World War V is Armageddon (Revelation 16:16).

He gathered them together into a place called in the Hebrew tongue Armageddon (Revelation 16:16).

When Antichrist sat in the temple, the Jews reject him as their leader (2 Thessalonians 2:3-4). After Antichrist and the Russia-Islamic coalition fight, they unite against Israel God pours out His bowl judgments. The 6th bowl dries up the Euphrates River. Then three demons from Satan, the Beast/Antichrist and False Prophet compel leaders to send armies to Armageddon (Revelation 16:14). See Unholy Trinity. About sixty miles north of Jerusalem is Mount Megiddo. Throughout history, there were over forty battles there. The armies gather in the Jezreel Valley before attacking Jerusalem. All nations are represented by a coalition that fights Israel.

The sixth angel poured out his vial upon the great river Euphrates; and the water was dried up, that the way of the kings of the east might be prepared. And I saw three unclean spirits like frogs come out of the mouth of the dragon… For they are the spirits of devils, working miracles, which go forth unto the kings of the earth and of the whole world, to gather them to the battle of that great day of God Almighty (Revelation 16:12-13, 14).

In Genesis 12, God promised to protect Israel and curse those who curse Israel. When the enemies of Israel attack, then Jerusalem is a burdensome stone. The battle is brutal for the Jewish people. Jerusalem will be plundered and captured but the people do not abandon the city.

Behold, I will make Jerusalem a cup of trembling unto all the people round about, when they shall be in the siege both against Judah and against Jerusalem. And in that day will I make Jerusalem a burdensome stone for all people: all that burden themselves with it shall be cut in pieces, though all the people of the earth be gathered together against it (Zechariah 12:2-3).

Behold, the day of the Lord comes, and your spoil shall be divided in the midst of you. For I will gather all nations against Jerusalem to battle; and the city shall be taken, and the houses rifled, and the women ravished; and half of the city shall go forth into captivity, and the residue of the people shall not be cut off from the city (Zechariah 14:1-2).

Once Israel turns to God, the weak become as strong as David and the house of David become as strong as God. The enemies will be in confusion and their horses blind. Then God will destroy the armies that attack Jerusalem.

In that day, says the Lord, I will smite every horse with astonishment, and his rider with madness: and I will open mine eyes upon the house of Judah, and will smite every horse of the people with blindness. And the governors of Judah shall say in their heart, The inhabitants of Jerusalem shall be my strength in the Lord of hosts their God.
In that day shall the Lord defend the inhabitants of Jerusalem; and he that is feeble among them at that day shall be as David; and the house of David shall be as God, as the angel of the Lord before them. And it shall come to pass in that day, that I will seek to destroy all the nations that come against Jerusalem (Zechariah 12:4-5, 8-9).

All seven trumpets have an element of atomic, biological and/or chemical weapons. At Armageddon, while the enemies stand, their bodies incinerate and they become dead men. This is the effect of an atomic bomb. Then Israel is rewarded by plundering the silver and gold of their enemies.

This shall be the plague wherewith the Lord will smite all the people that have fought against Jerusalem; Their flesh shall consume away while they stand upon their feet, and their eyes shall consume away in their holes, and their tongue shall consume away in their mouth.
And Judah also shall fight at Jerusalem; and the wealth of all the heathen round about shall be gathered together, gold, and silver, and apparel, in great abundance (Zechariah 14:12, 14).

The angel thrusts the sickle and the wrath of God harvests the earth. The devastation of Armageddon is described as a blood river flowing 180 miles by five feet deep.

The angel thrust in his sickle into the earth, and gathered the vine of the earth, and cast it into the great winepress of the wrath of God. And the winepress was trodden without the city, and blood came out of the winepress, even unto the horse bridles, by the space of [180 miles] (Revelation 14:19-20)

The end of the Tribulation comes with the 7th seal, 7th trumpet and 7th bowl. These judgments describe the lightning, thunder, hail and earthquakes as part of the Second Coming on Atonement.

> 7th Seal - Revelation 8:1, 5
> 7th Trumpet - Revelation 11:15, 19
> 7th Bowl - Revelation 16:17-18, 20-21
> Day of the Lord - Zechariah 14:1-15

Armageddon is the last battle and war of the Tribulation. All nations attack Israel and victory seems within their grasps. Everything seems lost for the Jews but God is faithful to His people. The Tribulation reminds us that even while judgment happens, mercy and grace is still available. The vast majority of people continue their rebellion against God but Israel and a remnant of Tribulation Saints choose to stand with God. At the Second Coming of Jesus Christ, all nations fall and Jesus Christ reigns.

References: 21st Century Revelation: World Wars, Iraq Wars & End Wars, Chapter 17 - Basic Bible Chronology, Chapter 20 - Players in the Game, Chapter 21 - Four Horses on the Run, Chapter 25 - Iraq War III, Revelation Outline, Timeline of the Tribulation, Tribulation, Revelation, Covenant, 21st Century View