Debating WWII grand strategy

Nice thick new book, 2016, entitled Commander in Chief, FDR's battle with Churchill.  Good photo of FDR on the dust jacket.   To read the book, you would think Roosevelt and Churchill spent the entire war squabbling over strategy.  
    From the get go, the Americans realized that the only way to defeat Germany was to land a huge army, on European soil, as close to Germany as possible, defeat the large and effective German army, drive for Berlin, and hang Hitler.   This kind of American thinking goes back to US Grant and the Civil War. Grant understood that the North had vastly greater reserves of manpower (and everything else that counted) than the South.  Once installed as commander in chief, Grant ordered the Army of the Potomac to march on Richmond, the southern capital.  Robert E. Lee put up a stout defense.   But after each bloody battle, Grant ordered his men forward and called up reinforcements.  Grant knew he could absorb horrendous casualties and still beat Lee and win the war.  It wasn't elegant, but it did work. 
   So the American thinking ran toward, "if you run into an obstacle, get a bigger hammer."  And starting a few days after Pearl Harbor, the American Joint Chiefs of Staff  became set upon the notion of a second front.  They even talked about launching the second front in 1942.  And in 1943.  They were dead set against peripheral operations that drained men and material away from the main objective. Things finally came together in 1944 at D-day.  In short it took two and a half years of preparation to build up the enormous force that triumphed in Normandy. 
   The British, who had suffered thru four years of trench warfare on the Western front, suffered the Germans to drive them into the sea at Dunkirk, and watched the Germans massacre the experimental raid on Dieppe, were not as sanguine as the Americans.  Churchill himself had commanded a regiment on the Western front, he knew how bad that sort of fighting could be.  Churchill was an imaginative guy, and he did a lot of thinking about ways to fight the Germans short of frontal attack across the Channel.  He came up with a bunch of them.  North Africa, Sicily, Italy, and Greece were all Churchill ideas.  I daresay there were others that didn't make the history books. 
   In 1942, it was clear to Churchill, and he made it clear to Roosevelt who was inclined to listen to Churchill, that the Allies needed to do something against the Germans that year.  It would have been politically impossible to spend the next two and a half years building up to D-day and not fighting the Germans anywhere.  And, the newly raised American divisions were green as grass, they needed some actual combat experience to become effective against the Germans.  Churchill proposed the Americans land an army in North Africa that year, drive east toward Montgomery's 8th Army, and crush the Axis forces between them.  In this case, Roosevelt had to go against the strong opposition of General Marshall, Admiral King and the US joint chiefs.  He did it, issued them a direct order, something Roosevelt seldom did.  And it worked.  The Germans were cornered in Tunisia, forced to surrender, and the Allies took as many prisoners of war as the Russians took at Stalingrad some weeks before. 
   This smashing success made the British even more reluctant to bet everything on D-day.  For the rest of the war,  conference after conference was held, with the British pushing for more peripheral operations and the Americans pressing for "do D-day now".   The Americans finally got their way, and D-day happened on the 6th of June 1944.  And it worked. 
   Nigel Hamilton goes over all of this in exhaustive detail.  He paints it as a struggle between Roosevelt and Churchill, and makes it sound so bitter that you wonder how the Alliance stayed together.  And he makes it sound like a whole new interpretation of history, which it isn't.  The debates between the British and the Americans are well documented and part of the generally accepted and understood history of WWII.