Brigadier General John Charteris CMG, DSO, was Sir Douglas Haig's Chief of Intelligence with the British Expeditionary Force GHQ, from 1915 to 1918. On the outbreak of the First World War, he followed Haig to the Western Front and became his aide-de-camp.

Charteris was soon asked by Haig to specialise in military intelligence, due to his fluency in French and German. He had no intelligence training or background, and was blamed by many during the war for Haig's military mistakes. Many argued that he told Haig exactly what he wanted to hear rather than what he needed to hear. His reports were considered to be optimistic, almost to the point of delusional, as he would write information based on very poor evidence. Charteris was greatly criticised but, even after his mistakes were exposed, Haig kept him as his Chief of Intelligence.

Major Desmond Morton, one of Haig's adjutants, recalled how Haig hated being told new information, especially if it went against his preconceived ideas, which probably explains why he kept Charteris in post. Yet Charteris' reports were partly to blame for the high casualties of the Somme in 1916. He tried to maintain Haig's morale by reporting that, as late as September 1916, the Germans would collapse before the end of the year. Haig believed him and continued with the offensive.

Again for the Cambrai Offensive of 1917, Charteris withheld vital information that he knew Haig wouldn't relish hearing. So after a few weeks, when the Germans regained the territory taken by the British, the offensive was deemed a failure. Charteris was blamed for 'intelligence failures', and in January 1918 was removed from his post and appointed as deputy director of transportation.

Brigadier Charteris' medals are, from left to right, Companion of the Order of St. Michael and St. George, Distinguished Service Order, 1914 Star, War Medal 1914-1920, Victory Medal 1914-1919 with Mention in Dispatches Oak leaf, Delhi Durbar 1911 Medal, Belgian Order of the Crown, Belgian Croix de Guerre, French Croix de Guerre, American Distinguished Service Medal, and Japanese Order of the Rising Sun.