During World War I, Bernard Baruch had the job of finding the best way to supply the war effort as efficiently as possible, making sure that the necessary raw materials would go where they would do the most good. His knowledge of supply and demand, as well as his personal acquaintance with many of the leaders of industry, were invaluable in helping to mobilize the United States and turn the tide of war in 1918. At the conclusion of the war, at the invitation of President Wilson, Baruch came to the Paris Peace Conference to try and negotiate a deal with the allies on the future fate of Germany. The leniency advocated by the Wilsonian delegation was vehemently opposed by the European nations that had suffered from the prolonged war, and Baruch returned with many unaccomplished goals.
It was at the conference that Baruch and Winston Churchill met face to face. Towards the later part of the war Churchill had been Minister of Munitions and together with Baruch helped to coordinate the distribution of war materials:
As my opposite number, as it were, in World War One, Churchill and I were in frequent cable communication. Those messages laid the groundwork for our subsequent close friendship (The Public Years, 71).