But the principal theme was clear and justifies the subtitle of "FDR's Battle With Churchill, 1943" - Churchill deliberately suppressed in his memoirs his continuous opposition to Roosevelt's insistence on a cross-channel invasion throughout 1943. Despite having agreed as much in Casablanca in January, Churchill fought repeatedly for a Mediterranean-centered strategy, advocating invasions of Sicily, Italy, Greece, the Balkans, and the Eastern Med - anywhere but France. Roosevelt agreed to an invasion of Sicily and later to limited operations in Italy, but refused to agree to anything else, understanding that Germany could not be defeated in peripheral battles, and thus setting the stage for the successful D-Day invasion in 1944.
The book also goes into great detail about the vision FDR had for the postwar power structure - something that Churchill was completely uninterested in, since he knew FDR has no place in it for a reconstructed British Empire. More importantly, FDR has the State Department develop that structure so that the Allied powers eventually became the United Nations. You won't find this in Churchill's memoirs, but it is well-supported by the private, contemporaneous writings by, among others FDR's son, the prime minister of Canada, and British and American military leaders.