Complex sentence: The Boer uprising caught by surprise the six small British forts scattered around Transvaal, housing some 2,000 troops between them, including irregulars with as few as fifty men at Lydenburg in the east where Anstruther had just left.
Split into simpler sentences: The Boer uprising caught the six small British forts scattered around the Transvaal by surprise. They housed some 2,000 troops between them, including irregulars with as few as fifty soldiers at Lydenburg in the east which Anstruther had just left.