Complex sentence: His flourishing cricketing career was waylaid however by the outbreak of the Anglo-Boer War, in which he served as a trooper with the Western Province Mounted Rifles where he was awarded the Queen's Medal for bravery.
Split into simpler sentences: His flourishing cricketing career was waylaid by the outbreak of the Anglo-Boer War. Tancred served as a trooper with the Western Province Mounted Rifles and awarded the Queen's Medal for bravery.