Charles Yorke undertook significant roles during the First World War, primarily as Military Secretary. He was instrumental in the planning and execution of military operations, and his competence in this role eventually led to his promotion to the rank of field marshal. This information is corroborated by the Wikipedia page dedicated to Charles Yorke, a British Army officer [1]. It is important to note that there were other notable individuals with the surname Yorke who have served in various capacities throughout history, such as Admiral Charles Philip Yorke, 4th Earl of Hardwicke [2], but the query specifically pertains to Charles Yorke's contributions during the First World War.