Complex sentence: On the way the guards deserted and many of the prisoners mistook this to be the liberation, however, the guards returned and fired upon those who had left the train, and ordered the others back onto the carriages.
Split into simpler sentences: On the way the guards deserted and many of the prisoners mistook this to be the liberation. However, the guards returned and fired upon those who had left the train, and ordered the others back onto the carriages.