My reading does not indicate Roosevelt was a great President, but he led a united country which, in spite of seeing war for over a year in Europe, entered WWII unprepared. They didn't even have a fighter to match the Hurricane let alone the Spitfire, Zero or ME109. But they were fast learners, as a united, smart country can be.
China will find a divided America easy prey, unlike Germany and Japan, who sewed the wind to reap a whirlwind. Trump has proven he will fight, the liberals and Chamber of Commerce will be content eating scraps from the dragon's table. That is proven.