The soldiers were “coming up to” Jesus in some formal manner such as would be done in giving homage to royalty. “Hail” was a common greeting (Matt 28:9 AV) but it was also an acclamation of royalty, an example being “Hail Caesar!” They are obviously mocking Jesus. Morris observes that they “doubtless conceived of themselves as witty fellows, able to devise an ironical situation. But the real irony is that the One whom they so mock is ‘King of kings, and Lord of lords.’” (Rev 19:11-16). Some day these same soldiers will again bow their knees to Jesus and proclaim Him to be King, but this time there won’t be any mockery in them (Php 2:10-11).  In its stead will be fear on their faces and tears in their eyes.

Matthew 28:9  (AV) And as they went to tell his disciples, behold, Jesus met them, saying, All hail. And they came and held him by the feet, and worshipped him.

Revelation 19:11-16  I saw heaven standing open and there before me was a white horse, whose rider is called Faithful and True. With justice he judges and makes war.  His eyes are like blazing fire, and on his head are many crowns. He has a name written on him that no-one knows but he himself.  He is dressed in a robe dipped in blood, and his name is the Word of God.
  The armies of heaven were following him, riding on white horses and dressed in fine linen, white and clean.  Out of his mouth comes a sharp sword with which to strike down the nations. “He will rule them with an iron sceptre.” He treads the winepress of the fury of the wrath of God Almighty.  On his robe and on his thigh he has this name written: KING OF KINGS AND LORD OF LORDS.

Philippians 2:10-11  that at the name of Jesus every knee should bow, in heaven and on earth and under the earth,  and every tongue confess that Jesus Christ is Lord, to the glory of God the Father.