The Greater Poland Uprising was like when kids in the playground get mad because they don't like the rules, so they make their own game. Only this wasn't just a game, it was about some grown-up stuff called freedom and national identity.
Many years ago, there was a place called Poland, but it wasn't really free since it was ruled by other countries. This made the people who lived there very unhappy. They wanted to be able to make their own decisions and have their own country.
In 1918, the Great War (now called World War I) ended, and the rulers of Poland's neighbors agreed to give up some land so that Poland could become a country again. This was great news, but the people in the region of Greater Poland wanted more. They wanted their own specific area to be its own country, and they were ready to fight for it.
So, they decided to start an Uprising, which is when people rise up against the people in charge to try and change things. It was like when a bunch of kids in the playground put their hands together and chanted, "We want change!"
The Polish people who were part of the Greater Poland Uprising were called insurgents. They were mostly farmers, workers, and students who had little to no military training, but they were determined to fight.
The insurgents took over some important cities and cut off communication lines to the foreign rulers. They also created their own government and started printing their own money. It was like they were making up their own rules as they went, just like kids say "I'm the king of this castle, and we're playing by MY rules!"
The fighting was tough, and many people lost their lives. But eventually, the insurgents were able to make their voices heard. The foreign rulers agreed to give them the region they wanted, and it became its own country called Greater Poland.
So, that's what the Greater Poland Uprising was all about. In short, it was like a group of kids who weren't happy with the rules deciding to create their own game and make their own rules. But in reality, it was much more complex and important because it was about people fighting for their freedom and independence.