He joined the
1st King's Dragoon Guards in 1895, and served as an
aide-de-camp to
Frederick Roberts during the
Boer War 1899–1900. He stayed as a
lieutenant of the 1st Dragoon Guards until January 1901, when he was seconded for service on the army staff as
Aide-de-camp to Lord Roberts, who had been appointed
Commander-in-Chief of the Forces. Lord Roberts resigned when this post was abolished in early 1904, and Petty-Fitzmaurice was promoted to
captain of his former regiment the 1st Dragoons in October 1904. In May 1902, he was part of a delegation led by the
Duke of Connaught to take part in the enthronement ceremonies in
Madrid for the young King
Alfonso XIII of Spain, and he was awarded the First class of the Spanish
Order of Military Merit. From 1909, he was an
equerry to the Prince of Wales (later
George V) until he was
killed in action in
World War I. ==Personal life==