Complex sentence: Lutosławski was mobilised with the radio unit at Kraków, and he was soon captured by German soldiers, but he escaped while being marched to prison camp, and walked 400 km back to Warsaw.
Split into simpler sentences: Lutosławski was mobilised with the radio unit at Kraków. He was soon captured by German soldiers, but he escaped while being marched to prison camp, and walked back to Warsaw.