If They Hadn’t Gone is an encyclopedia of biographical and statistical information covering 472 baseball players whose careers were affected by war. Its lists include brief biographies and lifetime stats for replacement-players who, before Pearl Harbor, would have been over-the-hill or below major-league quality. But, in war or in peace, baseball was the American pastime. Writing early in 1942, President Roosevelt urges Kenesaw M. Landis (then Baseball Commissioner) to play ball! for the sake of morale. Allen prints the letter in facsimile: It would be best for the country to keep baseball going, writes Roosevelt, even if the quality of the teams is lowered by the greater use of older players.