For some, a discussion on military intelligence and the First World War is the ultimate oxymoron. They might ask: when and where did generals display any use of intelligence? That the Battle of the Somme continued beyond the first day, they might argue, demonstrates a complete lack of military intelligence, or any other type of intelligence for that matter. If there ever was a war, they might add, where donkeylike officers led lion-like soldiers to slaughter against barbed wire, machine guns, and trenches, then the Great War was it. The oft told story of how Sir Launcelot Kiggell, Sir Douglas Haig’s chief of staff, upon seeing the Passchendaele battlefield and its sea of mud and carnage, reportedly wept, “My God! Did we send men to fight in that?” only to be answered by an aid: “It’s worse further up,” has lent credence to the position that the British high command was, indeed, incompetent. The myth that British generals were donkeys is an old one, and not likely to disappear completely anytime soon—at least in popular imagination. However, a study of combat intelligence should help to dispel this myth, for when intelligence was used wisely—as it usually was in the Canadian Corps—it increased the likelihood of success in the field. It did this by dispersing some of the fog of war and the resulting battlefield confusion. Good intelligence gave planners the details necessary for preparing the incredibly complex set-piece battles that were the hallmark of First World War combat. Such meticulous care and precision preparation ensured that there were fewer surprises on Zero Day, the day of attack, then otherwise would have been the case. By cutting through the fog of war, intelligence reduced the assaulting troops’ dependence on circumstance and luck, while restoring to commanders some degree of control over events in what was an otherwise highly chaotic environment. This was no small matter, especially on battlefields where communications were painfully slow, erratic and unreliable. Officers and men of the Great War faced conditions and technological advances that had completely altered warfare from what they had expected and trained for. To compensate, the Canadians, and others, used combat intelligence to help overcome such obstacles as poor communications, heavy machine-gun and artillery fire, entrenchments and barbed wire, and came to see it as a crucial element in waging successful trench warfare.