Complex sentence: The Webley Mk I service revolver was adopted in 1887, but it was a later version, the Mk IV, which rose to prominence during the Boer War of 1899--1902.
Split into simpler sentences: The Webley Mk I service revolver was adopted in 1887. Howeverm a later version, the Mk IV, rose to prominence during the Boer War of 1899--1902.