The prohibition movement preceded the First World War but gained new force with its onset. Using the language of war, prohibitionists urged Canadians to "use ballots for bullets and shoot straight and strong in order that the demon of drink might be driven from the haunts of men." They emphasized that those at home must make sacrifices just like those at the Front. Citizens should concentrate on fighting the war, not feeding their vices. Further, the manufacturing of liquor used up grain resources which could be used for the war effort  -  wheat was for feeding soldiers, not for making booze. Lastly, argued the prohibitionists, liquor robbed young soldiers of the vitality they needed to preserve their lives on the battlefield. (The fact that soldiers were given a shot of whiskey before being ordered to go "over the top" was conveniently ignored.) Women prohibitionists especially saw the opportunity to better their domestic spheres if prohibition were enforced, as alcohol abuse seemed to be the purview of men.

The prohibitionists' first victory came in Saskatchewan in 1915, followed quickly by Alberta the same year. Manitoba followed in February 1916. By the end of 1917, every provincial government except Quebec had implemented prohibition legislation. On April Fool's Day, 1918, a federal law was passed prohibiting the manufacture, importation, and transportation of any beverage containing more than 2.5 percent alcohol. Except for medicinal and sacramental needs, Canada was officially dry.

Despite the rum-running, the illegal trade, and increased doctors' prescriptions for alcohol for medicinal reasons, prohibition in Canada was effective. It brought a remarkable drop in criminal activity. Crime rates dropped from 2,369 per 100,000 in 1914 to 1,431 per 100,000 in 1918. In Calgary, arrests for drunkenness dropped from 1,743 in 1914 to 183 in 1917. Significantly, the police patrol of streets in that city was reduced from 63 to 28 constables. Jails were closed down, and Monday morning absenteeism dropped dramatically. The results were what prohibitionists had promised  -  in the lives of tens of thousands of Canadians, prohibition brought a social revolution.

By 1919, however, prohibitionist's hold was weakening as the postwar state proved unable and unwilling to maintain it. Returning soldiers, with visible and not-so-visible wounds had little tolerance for such puritan measures. Moreover, the law establishing prohibition had been an order-in-council, while prohibition was a wartime emergency. Thus, when the Wartime Measures Act was revoked in November 1919, the orders-in-council ceased to apply. Although prohibition was replaced by the Canada Temperance Act in 1919, it was more flexible than the order-in-council and shrewd Canadians with a taste for alcohol or money effectively exploited the loopholes. Most importantly, support for prohibition had weakened. In October 1920, British Columbia allowed liquor to be sold by the provincial government. That same month, the three Prairie provinces still voted "dry" but the majority in favour of prohibition had dropped considerably. Gradually, liquor came back to Canada, only this time the provincial governments received much more of liquor's profits.

Interestingly, the battle for prohibition was closely linked to the fight for women's suffrage. Both male and female prohibitionists saw women's suffrage as the key to achieving a dry nation. Like prohibition, women's suffrage acquired new force with the onset of the First World War and increased its support during the war years. Women reformers pointed out the inconsistency of fighting for democracy abroad when more than half of Canada's citizens were denied the democratic right to vote at home. Some suffragists employed nativist arguments, stating that if "unwashed hoards" of immigrants could vote, then surely could women of upstanding British background. Others argued that women also had served their country during the war and taken on tasks previously done by men; and if women were serving their country, they deserved the right to participate in its political life. Still other women suffragists argued that the war was caused by men's aggressive nature; if women had the right to vote and exercised political control, then wars would cease. As one of Canada's foremost suffragists and leading Prairie women, Nellie McClung, stated, the war was a direct result of male domination  -  "The hand that rocks the cradle does not rule the world. If it did, human life would be held dearer and the world would be a sweeter, cleaner, safer place than it is now." These maternal feminist arguments held much influence among many Canadians who were well aware of their nation's sacrifices in Europe.

Women's organizations rallied increasingly behind the suffragists' cause. The Women's Christian Temperance Association supported suffrage more enthusiastically than ever, linking it to the need to ban alcohol. Other associations like farm women's groups in the West also spoke out in defence of women's political rights. The most vocal suffragists were middle class and of British ancestry  -  the same group which was most deeply committed to the war.

Suffragists were eventually successful in obtaining the franchise for women. In January 1916, Manitoba became the first Canadian province to give women the vote. Saskatchewan and Alberta followed shortly thereafter in March and April, respectively. In 1917, British Columbia and Ontario gave women the vote, as did Nova Scotia in 1918, New Brunswick in 1919, and Prince Edward Island in 1922. In Quebec, women were denied the provincial franchise until 1940. Meanwhile, the Canadian government granted certain women the federal franchise in 1917 because the Wartime Elections Act enfranchised female relatives of those serving overseas. By January 1919, all women over the age of 21 were allowed to vote in federal elections. It was a watershed in Canadian history  -  approximately half the Canadian population was finally granted basic democratic rights.