 Kelly's cavalry unit was very effective and helped win one of their most significant victories of the Boer War at Paardeberg.He had a very successful career in the First Lifeguards and he was Mentioned in Despatches, receiving the Queen's South Africa Medal with six clasps, for his efforts in the Relief of Kimberley and the battles of Paardeberg, Wittebergen, Driefontein, Diamond Hill and Johannesburg.In the 1920s he turned his attention to politics becoming a member of the Cumann na nGaedheal party.