The Battle of Han Tui was an early battle in The War between the Fire Nation and the Earth Kingdom, where the Fire Nation forces were commanded by Fire Lord Sozin. Despite being outnumbered, the Fire Nation won the battle due to Sozin's military and tactical advantages.
Though very little is known about the battle, apparently the city of Han Tui was under siege by the troops of Fire Lord Sozin. Although his army was outnumbered, Sozin carefully calculated his advantages; a prolonged drought had both limited the supplies of the defenders and creating ideal conditions for a wildfire, while Han Tui's position downwind of the Fire Nation army meant that the flames would spread toward the city. With the defences completely obliterated in minutes, Sozin's forces then enclosed on the city and won the battle.
While the aftermath of the battle isn't made clear, Han Tui is thought to have been occupied by Fire Nation Military. Han Tui was later freed from the Fire Nation after the Battle at Wulong Forest and the crowning of Prince Zuko.