Complex sentence: Liss thought that swift reactions could not be expected from the "systematic French or the ponderous English" and used French and British methods, which made no provision for surprise and reacted slowly, when one was sprung.
Split into simpler sentences: Liss thought that swift reactions could not be expected from the "systematic French or the ponderous English". Liss used French and British methods, which meant no provision for surprise and slow reactions when one was sprung.