Complex sentence: Yeoman volunteered for service with the newly established Imperial Yeomanry in South Africa during the Second Boer War, and the lessons learned during the war led to the rebranding of the old yeomanry as the Imperial Yeomanry and a transition from a cavalry to a mounted infantry role.
Split into simpler sentences: Yeoman volunteered for service with the newly established Imperial Yeomanry in South Africa during the Second Boer War. The lessons learned during the war led to the rebranding of the old yeomanry as the Imperial Yeomanry and a transition from a cavalry to a mounted infantry role.