Byoir's college and legal training combined with his sales, advertising, publishing, newspaper reporting, and newspaper editing skills, made him Creel's publicity machine.
Byoir's first project was to solve CPI's printing problem. The Committee had the content for its pamphlets and newsletters, but no method to produce them during a backlog of wartime print jobs. Carl Byoir drew on his experience at The Hawkeyeand remembered printers who mostly worked on mail order catalogs had a slack period in early spring and fall. A contract was signed, and the deal saved CPI forty percent of their normal printing costs. For this and other creative solutions young Byoir became known as "the miracle man."
Other valuable public relations lessons were learned from Byoir's work with foreign ethnic groups. He was keenly aware that foreign-language groups had no knowledge of American institutions and war aims, so therefore they were not particularly sympathetic to the war effort. Byoir's success in the second selective service enrollment sealed his worth to CPI. His tactics included: newspaper advertising campaigns throughout the United States to reach three million estimated non-English speaking draft eligibles; 75,000 Four-Minute-Men who spoke every place the public assembled in the nation; six million notices sent to rural delivery boxes; and newsreel announcements shown to inform 30 million people of their obligation to the war effort.
His proudest contribution to the Committee was creating the League of Oppressed Nations--which was a representation of the various ethnic loyalty groups in the U.S. who had relatives in Europe under Austrian or German rule.
Following the war, President Wilson recognized Byoir's contributions to CPI and asked him to continue in the post-war fight for the minds of the people in Middle Europe.
Byoir was officially released from active duty with The Committee in March 1919, and he relied on his relationships formed there to keep him busy for the next few years.