Why did Germany continue to remain fragmented until the second half of the nineteenth century?

Throughout the entire period of history, from the Middle Ages to the New Age, Germany was a divided state. There was no political force in the country that would have sufficient authority to unite the country. There were so many fragmented and independent duchies and principalities that it was difficult to come to one solution. Nevertheless, in the 18-19th century, Prussia began to take an active position among the German states. Its political authority reached its peak in the second half of the 19th century. Then it was possible to unite the German lands.