Passage: The Wehrmacht controlled a much wider network of roads and railroads, centered on Smolensk and Roslavl. These two cities were important logistical centers, allowing quick supply and reinforcements for German troops. By far the most important railroads for German troops were the Smolensk-Bryansk axis and the Nevel-Orsha-Mogilev axis, linking German western troops with troops concentrated around Oryol.

Question: Why were the Smolen-bryansk axis and Nevel-Orsha_Mogilev axis so important to the German troops?
linking German western troops with troops concentrated around Oryol.