In the waning months of the Third Reich, in late 1944, acrimonious conflict was taking place out of public view in President Franklin D. Roosevelt’s Cabinet, among the secretaries of state, treasury and war (now called defense). According to presidential historian Michael Beschloss’ “The Conquerors: Roosevelt, Truman and the Destruction of Hitler’s Germany, 1941-1945,” at least two large issues in the anticipation of victory and the end of the war roiled American policymakers.

The first was the proposal by Treasury Secretary Henry Morgenthau Jr. to ensure that a militant Germany would never rise again to threaten the world, as it had done twice in the 20th century. His plan was to crush postwar Germany’s industrial infrastructure and return the country to an almost agricultural existence. Equipment would be carted off to Russia and other nations and the Ruhr Valley would be internationalized. Germany would be returned to a stage of development in which swords and lances might be the fiercest weapons.

The Morgenthau Plan, as it became known, was violently opposed by most of the American leadership, the British and the Russians, all of whom feared a resentful Germany thirsting for revenge. After all, many held the opinion that excessive humiliation and reparations heaped on Germany after World War I by the Versailles Treaty had directly paved the way for the ascent of Adolph Hitler, who fed on the German ache for vindication.

But there was more to it than that. Morgenthau was one of Roosevelt’s closest friends in government, a Hudson Valley neighbor who was only the second Jew to ever serve in a president’s Cabinet. Morgenthau was careful not to press his friendship with Roosevelt by making special pleadings on behalf of the Jews. But he was frustrated by the reluctance of his colleagues in the Cabinet, especially the state and war departments, to open America’s doors to Jewish refugees.

Seeing the president also disengaged from the growing tragedy of the death camps in Europe, Morgenthau pressed ahead with a plan to impose severe punishment on postwar Germany (including the immediate execution of the Nazi leaders) and to destroy its industrial capacity.

To one critic, who objected that the plan might create conditions for another Hitler and insisted that it was too harsh on the German people, Morgenthau replied that it was “not nearly as bad … as sending people to gas chambers.” The Germans themselves were hypocritically outraged at the plan, which had been leaked. They called it the “Jewish murder plan.”

Eventually Morgenthau lost his battle with the president and his colleagues. But Beschloss’ book curiously does not trace when and how the Morgenthau Plan was actually dropped in favor of the more lenient (and successful) Marshall Plan.

The other large issue that was being secretly adjudicated in the wartime Cabinet was the question of bombing the rail lines and camps such as Auschwitz,. Until now, it has been maintained that these discussions took place outside the president’s knowledge.

Presidential proponents (or apologists) have always maintained that John McCloy, assistant secretary of war, made the crucial decision not to attack Auschwitz, presumably because it would divert air-power resources from winning the war. But in a 1986 interview when McCloy was 91, it came out that the president had indeed been aware of the proposal and had soundly rejected it. If that is true, Roosevelt evidently made the call without consultation or having all of the facts at hand.

Indeed, as the reader makes his way through the internecine turf battles of the Roosevelt Cabinet, it occurs that this is not a story of the physical conquest of the enemy at all. Rather, it is on the destruction of the idea of Hitler’s Germany, and how the postwar nation had to be prevented from repeating its evil a third time. After the military trounced the Nazis, the next battle would be for the hearts and minds of postwar Germans.

The comparisons that might be made and the questions asked in light of the current involvement of the United States in Iraq are too obvious — and painful — to mention. The related acrimony among contemporary Cabinet subordinates to a wartime president is too astonishing to ignore.

“The Conquerors: Roosevelt, Truman and the Destruction of Hitler’s Germany, 1941-1945," by Michael Beschloss (400 pages, Simon & Schuster, $26.95).