It's just a classic end of the world scenario. It does not explicitly state WWII, with two other such conflicts before that as Mac said.
It states that everyone in the world will get in a fight. It says there will be two sides. That is pretty much a world war.
Revelations 16:13 And I saw three unclean spirits like frogs come out of the mouth of the dragon, and out of the mouth of the beast, and out of the mouth of the false prophet.
16:14 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.
Gathering "All the Kings of the Earth". Good luck with just a figurehead, but there is the gathering, at another point they are fighting.
19:12 His eyes were as a flame of fire, and on his head were many crowns; and he had a name written, that no man knew, but he himself.
19:13 And he was clothed with a vesture dipped in blood: and his name is called The Word of God.
19:14 And the armies which were in heaven followed him upon white horses, clothed in fine linen, white and clean.
19:15 And out of his mouth goeth a sharp sword, that with it he should smite the nations: and he shall rule them with a rod of iron: and he treadeth the winepress of the fierceness and wrath of Almighty God.
19:16 And he hath on his vesture and on his thigh a name written, KING OF KINGS, AND LORD OF LORDS.
19:17 And I saw an angel standing in the sun; and he cried with a loud voice, saying to all the fowls that fly in the midst of heaven, Come and gather yourselves together unto the supper of the great God;
19:18 That ye may eat the flesh of kings, and the flesh of captains, and the flesh of mighty men, and the flesh of horses, and of them that sit on them, and the flesh of all men, both free and bond, both small and great.
19:19 And I saw the beast, and the kings of the earth, and their armies, gathered together to make war against him that sat on the horse, and against his army.
19:20 And the beast was taken, and with him the false prophet that wrought miracles before him, with which he deceived them that had received the mark of the beast, and them that worshipped his image. These both were cast alive into a lake of fire burning with brimstone.
19:21 And the remnant were slain with the sword of him that sat upon the horse, which sword proceeded out of his mouth: and all the fowls were filled with their flesh.
And there everyone else dies. Every nation gathering to fight sounds like a world war.
