Okay kiddo, let me tell you a story about something called 1453 Fennia.
Once upon a time in Europe, there was a big empire called the Byzantine Empire. They were very powerful and had a lot of land, including a city called Constantinople.
One day in the year 1453, another empire called the Ottoman Empire decided they wanted to take over Constantinople. They had a big army and they surrounded the city, making it hard for anyone to come in or out.
The people inside Constantinople were scared because they knew the Ottomans were strong and it was hard for them to get help from others. They tried to fight back with their own army, but it wasn't enough.
After a long time of fighting, the Ottomans eventually broke through the walls of Constantinople and took control of the city. This was the end of the Byzantine Empire.
So, 1453 Fennia is just a fancy way of talking about the year 1453 and what happened in Constantinople. It was an important event in history because it changed who was in charge of that part of the world.