In ancient times a white horse was used by a conquering king who would ride into a city conquered.

The Scripture indicates that Jesus will return on a white horse, but we know this rider cannot be Jesus because he is the first of four riders that are sent as a judgment at the beginning of the tribulation. Jesus comes back to end the tribulation by destroying all the wicked ones gathered in Israel,– but to judge the people of the earth, separate the sheep from the goats and set things right.

Rev 6:1-2: “Now I saw when the Lamb opened one of the seals; and I heard one of the four living creatures saying with a voice like thunder, "Come and see." And I looked, and behold, a white horse. He who sat on it had a bow; and a crown was given to him, and he went out conquering and to conquer.”

Notice it is the lamb that opens the seals, the first rider is sent is to conquer. The next riders, red horse kills; the third rider on a black horse has a scale, he determines the price of basic food and luxuries. The fourth rider is a pale horse, who is Death, and Hades followed with him. And power was given to them over a fourth of the earth, to kill with sword, with hunger, with death, and by the beasts of the earth.” The judgements are incremental and are sent from the lamb but are not involving the lamb himself.

When Jesus returns to the earth at His Second Coming, to end the Tribulation period, He will bring others with

Him from Heaven that will sit on white horses:

Rev. 19:4, there is an army that follows Him riding on white horses, clothed in fine linen, white and clean. In v.8 we are told the fine linen is the righteousness of the saints. The saints are returning with Christ, and He is to wage war on the Antichrist, and his armies. This is reffered to in 2 Thess.2:8: “then the lawless one will be revealed, whom the Lord will consume with the breath of His mouth and destroy with the brightness of His coming.”

VV.11-16 “Now I saw heaven opened, and behold, a white horse. And He who sat on him was called Faithful and True, and in righteousness He judges and makes war. His eyes were like a flame of fire, and on His head were many crowns. He had a name written that no one knew except Himself. He was clothed with a robe dipped in blood, and His name is called The Word of God. And the armies in heaven, clothed in fine linen, white and clean, followed Him on white horses. Now out of His mouth goes a sharp sword, that with it He should strike the nations. And He Himself will rule them with a rod of iron. He Himself treads the winepress of the fierceness and wrath of Almighty God. And He has on His robe and on His thigh a name written: KING OF KINGS AND LORD OF LORDS.”

This is describing Armageddon, when Jesus comes back and puts away evil.

Who are the white horses? They are not earthly horses but angelic creatures that are from heaven. In the same manner angels have animal like features (Cherubim), there are an array of creatures that dwell in heaven. Cherubs have wings;

 “And He rode upon a cherub, and flew; he flew upon the wings of the wind” (Ps 18:10, also 2 Sam. 22:11)

So the first rider on the white horse conquers at the beginning of the tribulation as a judgment , he is not Jesus. But Jesus comes back on a white horse to end the Tribulation by judging the evil ones that have taken control of the earth. He will then separate the sheep from the goats in the coming days (Mt.25) and set up his kingdom with the saints.