Encompassing some 102,000 square miles in Northern Ukraine and into Southern Belarus, it served as a nature barrier for invading armies to avoid. Or as the Germans called it Pripjet-Sümpfe during the invasion of the Soviet Union in 1941. But as they retreated back West, several units were forced thru the swamps to escape with what they could carry. Most likely diseases caused just as many casualties vs enemy fire. Probably made more famous decades later with the fallout of the Chernobyl nuclear accident in 1986, which was located just south.
What? problem for both armies to cross. Of course in the beginning for blitzkrieg but later also for the Red Army
