"Finally, just a note ... research the "Zimmerman Telegraph" as the trigger for the US entry into WW I. "
Say what? Lusitania was sunk in 1915. Roosevelt and Churchill were both then in charge of their respective Navies. What's the point?
The Zimmerman telegram was passed from British intelligence to the Americans -- could that be "suspicious"? Possibly, except that the Germans themselves have confirmed its accuracy.
A. Wilson's administration knew at the time of her sailing that she had tons of munitions, aka contraband. That made her a legitimate target in a war zone.
Said knowledge was denied until the mid-1970's when a British underseas film crew released some of the photographs of her damage and cargo.
As if by magic the US government then "finds" her original cargo manifest. Seems the files had fallen behind a old file cabinet decades prior.
Imagine that. Imagine how many people knew. Imagine how that "secret" was kept for well over a half-century.
B. FDR was never "in charge" of the US Navy - that is, he was never Secretary of the Navy.
But, your question - think of the SS LUSTANIA as On-The-Job Training for FDR and WSC. And oh, what lessons they learned.
C. To this day the Admiralty has yet to release all of the SS LUSITANIA papers - coming up on a full century. See "Room 40"