The Lanny Budd series of eleven novels was published from 1940 through 1953. Its fictional protagonist is the heir of an American munitions fortune, but his adventures take him through real places meeting real people all over Europe from WW1 through WW2. I am not yet halfway through the first volume but consider the series a masterpiece and his Pulitzer well-deserved. Elbert’s political history writings echo Sinclair’s in so many ways, perhaps because they were contemporaries and lived in southern California and shared many interests. But I suspect they were personal friends as he got the birth data from the source.