Complex sentence: Helfeld and Lepidus continued their flight along the south side of Banbury Reservoir; as they crossed an area of open land, they sheltered behind a haystack and held off the pursuers, who numbered about 20 at this point.
Split into simpler sentences: Helfeld and Lepidus continued their flight along the south side of Banbury Reservoir. As they crossed an area of open land, they sheltered behind a haystack and held off the pursuers, who numbered about 20 at this point.