So imagine you are playing a game of capture the flag with your friends. You have to protect your flag from the other team, while trying to capture their flag too. The Battle of Haengju was a big game like that, but with a whole bunch of soldiers instead of just you and your friends.
In the Battle of Haengju, there were two teams. One team was the Koreans, and the other team was the Japanese. They both wanted to control a really important place called Haengju. It was like the flag in your game of capture the flag – whoever controlled Haengju controlled a big part of the area around it.
The Korean team had fewer soldiers than the Japanese team, but they had a really good plan. They built a big wall around the place they were defending. This made it really difficult for the Japanese team to get in and attack them.
Even though the Japanese team was bigger, they couldn't get past the wall to capture Haengju. The Koreans were really good at shooting arrows and throwing rocks from the walls, so the Japanese team couldn't get close enough to fight them. The Koreans kept defending for days and days, and the Japanese team was stuck outside the walls, unable to get in.
At the end of the battle, the Japanese team had to give up because they couldn't get past the wall. The Koreans had won the game! They were able to keep control of Haengju, and this made them very happy. The Battle of Haengju was an important moment in Korean history, because it showed that even when they were outnumbered, they could still win if they had a good plan and worked together.