[1] As a member of the naval brigade he was part of the force sent to relieve Eshowe and was present at the Battle of Gingindlovu, so receiving the South Africa medal.

[3] He fought in the Boxer Rebellion in 1900 as flag captain to Rear-Admiral Sir James Andrew Thomas Bruce and commander of HMS Barfleur (1899–1902).

[1] It was announced in the 1902 Coronation Honours that he would be appointed a Companion of the Order of the Bath (CB) dated 26 June 1902,[4][5] and he received the actual decoration after his return home, from King Edward VII at Buckingham Palace on 24 October 1902.

[7] During his tour, a German officer, Lieutenant George von Hase, was selected to accompany Warrender and act as his aide and translator.

Hase was required to write a report about Warrender and other British officers he met, and later wrote a book describing the visit.

Warrender was noticeably deaf: He could understand his staff without problem, but could sometimes have difficulty with other officers and strangers, particularly in a noisy environment such as a party.

Hase was instructed by Warrender to convey an invitation to Admiral von Ingenohl for any German officers who wished to visit and inspect the British ships.

However, Hase reported that he was friendly with Commander Brownrigg, the gunnery officer, was happy to show him around almost all the ship, except for the 'firing director' which was regarded as strictly secret.

[8] On the afternoon of 28 June news arrived of the assassination of Franz Ferdinand, who had been a friend of the British ambassador to Germany, Edward Goschen, who was also staying on George V. A discussion ensued at which Hase was present, where Warrender warned of the likelihood that many European countries would now be drawn into a war.

In the evening Warrender attended the official Imperial Yacht club dinner, now presided over by Prince Henry, in the Kaiser's absence.

He observed that the preparation of Scapa Flow as a long range naval base for the blockade of Germany, had been suggested by German officers.

[10] Shortly after the Kiel visit Warrender temporarily commanded the Grand Fleet ordered to move to Scapa Flow after annual exercises, when a declaration of war was considered imminent.

He married Lady Ethel Maud Ashley Cooper, daughter of Anthony Ashley-Cooper, 8th Earl of Shaftesbury, on 6 February 1894 at St. Paul's Church, Knightsbridge, London.