Professor Hale called for war in September 1914; in January 1915 he was in partial agreement with former President Theodore Roosevelt on the need to act against the German Empire.

But like fellow progressive Alfred Hayes, Jr., William Gardner Hale viewed the American role as supporting the internationalist and multilateral position represented by the Hague Conventions.

[8] In May 1916, Hale agreed to serve as an honorary vice president of the American Rights Committee during its Carnegie Hall memorial protest of the Lusitania sinking by a German Navy U-Boat.

The purpose of the mass meeting was to organize a petition to President Woodrow Wilson demanding an end of diplomatic relations with the Imperial Court at Berlin.

Hale's position was based on his concern that Hughes would draw the United States into another war with the Republic of Mexico and that Wilson, while not supportive enough of the Allies in Europe, "had the high aim of building up a national life in which, while honest business shall have every opportunity, privilege shall not rule the poor and the weak.

"[10] Hale was a member of the New England Anti-Imperialist League, as well as the Phi Beta Kappa Society, the German Archaeological Institute of Berlin, Athens and Rome, and the American Philological Association (APA).