National Library of Scotland, a newcomer to the Commons, uploaded a series of images of World War I. The photographs mostly show activity behind the front lines, such as soldiers resting or supply trucks being loaded. One series of photographs shows carrier pigeons. During World War I, this proved to be a more reliable way of transmitting information from advance units than telegraphs or other methods. According to the text on this photo of a French pigeon trainer, "On September 11, 1914, the French gave 15 pigeons to the British Intelligence Service. By 1918 there were some 20,000 birds and 380 expert pigeon trainers in the British Army alone."
Photos link through to the original images.