At 7:28am on July 1st, 1916 the Battle of the Somme started with explosion of 17 massive 'mines' underneath enemy territory. Lochnagar was the largest of these. It remains "The largest crater ever made by man in anger".
British. A Careless talk poster, illustrated with civilian and armed forces headgear, with the slogan ‘The more information you keep under your hat' (trilby hat) and the caption ‘the safer he'll be under his' (steel helmet). As with many Careless talk posters, the images focus on the head area, indicating whatever knowledge was contained in the head, it should be kept there.