Complex sentence: General Lord Roberts was appointed Commander in Chief of the British forces in South Africa and moved to take personal command of this front, subsequently lifting the Siege of Kimberley and forcing Cronje to surrender at the Battle of Paardeberg.
Split into simpler sentences: General Lord Roberts was appointed Commander in Chief of the British forces in South Africa and moved to take personal command of this front. He subsequently lifted the Siege of Kimberley and forced Cronje to surrender at the Battle of Paardeberg.