Isaiah 63:3 - Ellicott's Commentary On The Whole Bible

I have trodden the winepress alone... — The “winepress” is here, as elsewhere (Joel 3:13; Lamentations 1:15; Revelation 14:18-20), the received symbol of the carnage of battle. What the hero-conqueror asserts is that the battle was fought by him single-handed. He had no human allies, but God was with him. A slight change in the vowel-points, adopted by some interpreters, turns the verbs into futures: “I will tread ... will trample, ...” as in the second clause of the Authorised Version. It is better, perhaps to take the latter verb also as in the past. The work of slaughter is clearly thought of as accomplished before the warrior is seen.