Original: Three years later, in South Africa during the Second Boer War, Baden-Powell was besieged in the small town of Mafeking by a much larger Boer army (the Siege of Mafeking).
Simplified: Three years later during the Second Boer War, Baden-Powell was besieged in the small town of Mafeking by a much larger Boer army (the Siege of Mafeking).