"There is a lot of "He's" in that statement."

The three Presidents in question were men. I didn't think the grammatically neutral he/she was necessary.

"Even the "America First Committee" which included Charles Lindbergh, objected to FDR declaring war against Nazi Germany."

Hence FDR did not make the first move to declare war on Nazi Germany. Note, the speech that Lindbergh was meant to give on 12 December in support of the America First movement was cancelled, and Lindbergh sought to be reinstated as an officer as America went to war against the Axis powers. The America First Committee disbanded in the face of the declarations of war against the US. They didn't have much of a leg to stand on in terms of convincing the American public to support their agenda. And, throughout the war, FDR (another he) and his administration did a pretty good job of maintaining public support -- notwithstanding some pretty withering criticisms from, for example, the Hearst newspapers (featuring, on occasion, Doug McCarthy, who spoke out in an article in one of them on the incompetence of the Navy/Marine Corps amphibious ConOps in the aftermath of Tarawa).

Russell Weigley posits the notion of an American Way OF War (American in Bellum, if you will). I would submit that there is an American Way TO War (American ad Bellum) -- that is, the best way that America goes to war -- usually in response to an "unprovoked" attack, which awakens the sleeping giant from its peaceful slumber to fight the evil in great righteousness. Americans, I would submit, aren't altogether keen on the idea of being the first to cross the line of departure, but neither are they particularly keen to turn the other cheek once they've been kicked upside the head.