Educated at St. Paul's School, he earned his doctorate at Harvard University in 1928, where he studied under the influence of Charles Howard McIlwain.
[6][7] Birdsall died at the age of seventy in Christiansted, United States Virgin Islands, where he had been in retirement for eight years.
He is chiefly remembered for Versailles, 20 Years After, as well as a number of articles on the diplomacy of Woodrow Wilson.
His sister Jean Birdsall was also a historian, having received her doctorate and serving as associate professor at Vassar until her death in 1935.
The American Historical Association awards a biennial prize in his honor to the author of the most important work on European military or strategic history since 1870 by a citizen of the United States or Canada.