To block the French, a British force under Herbert Kitchener was sent to conquer the "Mahdiyah" state and defeated the "Ansar" at the Battle of Omdurman in 1898. It was thus their rivalry with the French, not a desire to "avenge Gordon" that led the British government to annex the "Mahdiyah" state in 1898. However the British public and Kitchener himself saw the expedition as one to "avenge Gordon". As the Mahdi was long dead, Kitchener had to content himself with blowing up the Mahdi's tomb as revenge for Gordon's death. After the Battle of Omdurman, Kitchener opened a letter from the Prime Minister, Lord Salisbury, and for the first time learned the real purpose of the expedition had been to keep the French out of the Sudan and that "avenging Gordon" was merely a pretext.