The Battle of Breitenfeld happened a long time ago in the year 1642. It was a big fight between two groups of people called the Swedes and the Germans. They were fighting because they both wanted to be in charge of a place called Saxony.
The Swedes were led by a man named Gustavus Adolphus, who was really good at leading his army. He had a lot of soldiers and they were very well trained. They also had cool weapons like guns and cannons.
The Germans were led by a man named Johann Tserclaes, who was also very good at leading his army. They had a lot of soldiers too and they also had cool weapons like swords and spears.
The two armies met at a place called Breitenfeld and they started to fight. It was a very big battle with lots of noise and smoke from all the weapons firing. The soldiers were shouting and running around trying to win the battle.
At first, it looked like the Germans were going to win because they had more soldiers and they were very skilled in using their swords and spears. But then, the Swedes used their guns and cannons to shoot at the Germans from far away. This gave them an advantage and they started to win the battle.
In the end, the Swedes won the Battle of Breitenfeld and they became the rulers of Saxony. It was a very important battle because it changed the course of the war and made Gustavus Adolphus famous as a great military leader.