The Canadian Expeditionary Force was mostly volunteers, as conscription was not enforced until the end of the war when call-ups began in January 1918 (see Conscription Crisis of 1917). Ultimately, only 24,132 conscripts arrived in France before the end of the war.Canada was the senior Dominion in the British Empire and automatically at war with Germany upon the British declaration. According to Canadian historian Dr. Serge Durflinger at the Canadian War Museum, popular support for the war was found mainly in English Canada. Of the first contingent formed at Valcartier, Quebec in 1914, 'fully two-thirds were men born in the United Kingdom'. By the end of the war in 1918, at least 'fifty per cent of the CEF consisted of British-born men'. Recruiting was difficult among the French-Canadian population, although one battalion, the 22nd, who came to be known as the 'Van Doos', was French-speaking ("Van Doo" is an approximate pronunciation of the French for "22" - vingt deux) Private Joseph Pappin, 130 Battalion, Canadian Expeditionary Force. To a lesser extent, several other cultural groups within the Dominion enlisted and made a significant contribution to the Force including aboriginals of the First Nations, Black Canadians as well as Black Americans. The CEF eventually numbered 260 numbered infantry battalions, two named infantry battalions (The Royal Canadian Regiment and Princess Patricia's Canadian Light Infantry), 13 mounted rifle regiments, 13 railway troop battalions, 5 pioneer battalions, as well as numerous ancillary units including field and heavy artillery batteries, ambulance, medical, dental, forestry, labor, tunneling, cyclist, and service units.A distinct entity within the Canadian Expeditionary Force was the Canadian Machine Gun Corps. It consisted of several motor machine gun battalions, the Eaton's, Yukon, and Borden Motor Machine Gun Batteries, and nineteen machine gun companies. During the summer of 1918, these units were consolidated into four machine gun battalions, one being attached to each of the four divisions in the Canadian Corps.The Canadian Corps with its four infantry divisions comprised the main fighting force of the CEF. The Canadian Cavalry Brigade also served in France. Support units of the CEF included the Canadian Railway Troops, which served on the Western Front and provided a bridging unit for the Middle East; the Canadian Forestry Corps, which felled timber in Britain and France, and special units which operated around the Caspian Sea, in northern Russia and eastern Siberia.