The outbreak of war in 1914 came at a fortuitous time for Hoover. The mining boom in both precious and base metals was beginning to spend itself, except perhaps in Russia. He was thinking now of employing in some philanthropic way his skill in public relations, tested at Stanford and refined in his years of mining promotion. An admirer of Theodore Roosevelt's progressivism, he had been thinking for some years of government service in appointive office. He was in London when war broke out in August, and the American ambassador, Walter Hines Page, asked him to aid Americans who had been stranded abroad at the onset of war. He did this with such efficiency that Page recommended to President Wilson that Hoover be drafted to help provide food for the Belgians, hitherto dependent on the importing of food, after the invasion of their country.
For the next three years Hoover headed the Commission for Relief in Belgium (CRB). Despite the stubbornness of both Germans and British, Hoover, using highhanded and sometimes illegal methods, employed his knowledge of worldwide shipping to bring a steady flow of food to the tiny country. He brought to his work ample technical and administrative skills, but more particularly the relentless energy and forcefulness of his personality. "This man," stated his German passport, "is not to be stopped anywhere under any circumstances."
The relief of Belgium, Hoover enthusiastically proclaimed, was "the greatest job Americans have undertaken in the cause of humanity." The result would be "the greatest charity the world has ever seen." Hoover himself remained shy and averse to publicity. He had, so it seemed, the simple Quaker distaste for such things: in Quakerism good works become tainted if publicized. All his life Hoover made a secret of his hundreds of benefactions.
Unquestionably an ambitious man, Hoover sought from President Wilson the post of United States food administrator even before the country formally entered the war in April 1917. Wilson, who could not question the effectiveness of the CRB, gave Hoover the job. Hoover realized that his earlier work in Belgium was a useful model for wartime administration and that his own reputation for being the "Great Engineer" put him in a unique position to help win the war. His name had become synonymous with thrift and self-denial, so that "Hooverize" came to mean "economize for a worthy purpose."
Propaganda was the main weapon of the Food Administration. It preached meatless and wheat-less days. A massive campaign enjoined those in control of households to cut down especially on the normal use of bread and sugar, and schools and churches joined the crusade. Yet Hoover, while preferring volunteerism, hastened to get congressional legislation, such as the Lever Food Control Act of 1917, which set a government-guaranteed price for wheat.
In 1919, Hoover managed to dispose of much of the wartime food surplus by selling it to European governments, which often borrowed from the United States for the purpose. Whatever the merits of the transaction, Hoover's American Relief Administration (ARA)—a public agency replaced in mid-1919 by a private one bearing the same name—got the job done as well as could be expected. Hoover went to Europe, slashing through red tape everywhere he went. Without functioning European systems of transportation and communications, he had to create his own. Hoover violated laws, made laws, and transgressed the sanctity of international boundaries to get food to where it was most needed. He implicitly urged his subordinates to do likewise and to ignore local or centralized authority.
The Versailles Peace Conference, particularly its representatives from France, urged Hoover to withhold food to discourage the advance of bolshevism in eastern and central Europe. Whether Hoover consistently did so is still a matter of controversy. Hoover's most blatant use of food for political purposes was against a coup d'état by the reactionary Hapsburg monarchy in Hungary. For Hungary, under the leadership of the Bolshevik Béla Kun, Hoover allowed food that had already been purchased to be taken into the country, although the practice ceased after he received explicit directions from Paris not to allow it. By mid-1919, after Kun had ordered hundreds of political executions, Hoover's concern for feeding Hungary had ceased, and he welcomed the government's overthrow by radical trade unions. To him anything was preferable to an Allied invasion of these troubled lands. Hoover's insistence on feeding starving Germans received sharp criticism from the Allies. While he gave some preference to feeding the war-torn nations that had fought with the Allies, he bent the will of Versailles statesmen who would have allowed Germans to starve.
A subsequent episode in Hoover's relief efforts came in Soviet Russia during the great famine of 1921–1923. When the Soviets guaranteed freedom of movement to the ARA, shipments began in huge quantity. When a shrill anti-Communist complained at a public meeting about what Hoover was doing, he replied, "Twenty million people are starving. Whatever their politics, they shall be fed." George Kennan later observed that the ARA "importantly aided" the revolutionary government, "not just in its economic undertakings, but in its political prestige and capacity for survival."