A fifth division was later organized in England, but was there held as a reserve, most of its constituent elements being sent to France as reenforcements to the first four divisions. The Canadian Cavalry Brigade was not organized until early in 1915, in England, but its constituent parts had come over from Canada with the first contingent. From the time of its formation until May, 1918, it was under the command of Brigadier General (later Major General) J. E. B. Seeley, C. B., C. M. G., D. S. O., M. P., a veteran of the South African War, where he served under Sir John French, and later Secretary of State for War in the Asquith Cabinet. The brigade was originally formed from the Royal Canadian Dragoons, Lord Strathcona's Horse, King Edward's Horse, an Imperial unit, and the Royal Canadian Horse Artillery. In 1916 the King Edward's Horse left the brigade and its place was taken by the Fort Garry Horse, previously known as the Canadian Reserve Cavalry Regiment. Later the brigade had added to it the Machine Gun Squadron, the Canadian Cavalry Field Ambulance, and the Mobile Veterinary Section. During the early part of its services in France the brigade operated as infantry, and it was not till the early part of 1916 that it was finally reconstituted as a cavalry force. The cavalry brigade ranged in numbers from two to three thousand throughout the war. CHAPTER VII CANADA'S HUGE FORESTRY CORPS Of the special corps, outside the regular classifications into which all armies are subdivided--infantry, cavalry, artillery, etc., special emphasis and more detailed description should be accorded the Canadian Forestry and the Canadian Railway Corps. The extraordinary dimensions which these arms of the service acquired must be considered when the number of Canadian troops on the actual field of battle is compared with those who did not reach the front. No general history of the war can ever be written without devoting considerable space to these two corps as factors which assumed much importance in the defeat of Germany. In the production of lumber, and in the building of railways, to keep up with the rapid westward progress of the Canadian population, Canada stands forth preeminent. It was only natural that the special skill and knowledge acquired in these industries should be in strong demand by the Allied forces in general, and it was Canada which could supply it in the greatest measure. Hence the unusual number of Canadian recruits who were diverted to these particular branches of military service. The formation of the Forestry Corps came about through the growing shortage of shipping. In February, 1916, the British Government issued a proclamation restricting certain imports, for the sake of economy in shipping. One of the chief commodities affected was timber, of which six million tons was being brought into the country annually.