Oh joy! I love "what ifs!"
OK, here's my "what if":
February, 1943. Tunisia and Stalingrad are now bitter memories for the Germans. Seeing the Fuehrer's inept handling of the two active fronts, frustrated with events all round (less von Manstein's clever handling of the mobile defensive in southern Russia), Hitler is assassinated later that year.
Following a visit to the front in Spring 1943, Hitler's Ju-52, complete with fighter escort, is heading back to Berlin. On board, known only to a few, are some pressure activated bombs, hidden in Cognac bottles. The planes encounter a storm front, and ready to go "under" the storm to avoid some heavy clouds. Just as the planes are about to go lower, the pilot notes a clear patch a bit farther south. He reckons that there is a good tail wind there, making the long flight that much shorter. He announces the change to the fighter pilots and throttles up to gain altitude. As the aircraft climbs, he suddenly hears a lound explosion from within the plane. He is losing control of the aircraft as it begins to lose altitude. He sends out his SOS, announcing that his engine has caught fire and exploded. The Fuehrer is quickly roused from his sleep and his aides begin to strap a parachute to him. The plane is bucking and yawing so much that they are not successful. The planed explodes in a firey ball in the Pripjet marshes. All aboard are killed instantly.
There is chaos in Berlin as the news reaches every headquarters. von Manstein, flush with victory at Kharkov, is recalled to Berlin and due to his being one of the few Field Marshalls with a perfect record, is appointed to the OKW.
The politicos at the high end of the Nazi Food Chain begin to posture for position. In the end, a nervous (and drug addicted) Hermann Goering is nominated Fuehrer. He instantly begins to meddle in the military matters of the conduct of the war, but due to some clever background manoeuvring (and some spiking of his heroin cocktails), "Dicker Hermann" begins to slip only into the realm of "Grand Strategy" and "International Politics". Speer takes over manufacturing as von Manstein, Guderian et al consider the future of the war, less half a million fine young soldiers now permanently struck off the order of battle.
After careful consideration, they make some very key decisions:
First, due to careful examination of events over the previous year, they decide that ENIGMA is somehow compromised. ENIGMA II is prepared for use. In the meantime, transmissions are sent using veiled speech, the U Boats are recalled with "fixed" orders awaiting the issuing of ENIGMA II. As well, "fake" ENIGMA transmissions and directives are sent, and the Western Allies are none the wiser.
Next, the main effort will continue to be the war in the east. von Manstein's plan for a "Back hand blow" is accepted and put into place for the upcoming summer. Though the German forces remain quite powerful, they lack sufficient strength to bash through the Russian defenses. Through a set of strategems, the Russians are lead to believe that a massive offensive will be mounted around Kursk.
The secondary effort is set at the blunting of the Anglo/American air offensive. Here Speer initiates development and production for "Wasserfall", a radar guided anti aircraft rocket. First use is anticipated for October, 1943. The Germans just hope that it isn't too late by then.
The next priority is the Atlantic Wall. Rommel is dispatched to "do his thing" and starts by strengthening the wall and gets his wish for panzer and panzergrenadier units to be pushed forward in order to meet the invasion, expected for May 1944 at the earliest, at the beaches.
The "offensive" at Kursk kicks off on 5 July 1943. The Russians commit to their counteroffensive, and learn only on 7 July that the "offensive" was nothing more than a demonstration. Their forces make great headway and more and more units are thrown into the breach by Stalin, including the strategic reserve, the 5th Guards Tank Army. After an advance of 200 km in some areas, and in spite of warnings from the STAVKA that the German offensive was nothing but a ruse, Stalin "dismisses" the naysayers and installs a batch of sycophants in their place. He announces that the Red Army has achieved mastery over the Wehrmacht, even in the summer months.
On 10 July, the same day that Anglo-American forces invade Sicily, the Germans launch their real offensive in the east. Gone are the lofty goals of oil fields in Asia; their goal now is the destruction of the Red Army. By 12 July, they have sealed the trap and some five complete armies are encircled. There are no untrapped forces left who can assist in a break out, even though Stalin would have none of that. Attempts to "link up" are foiled by layers of German AT defences as von Manstein expertly husbands the forces available.
In Sicily, the Anglo American forces are able to advance, albeit slowly in the face of a skillful delaying action: trading infantry space for time.
By the end of August, 1943, the Russian Forces trapped in the so-called "Poltava" pocket begin to show signs that they are soon to be destroyed. After yet another failed breakout attempt, the pocket begins to contract. The Germans tighten the noose, and begin to reduce it with patience, employing the large siege artillery used the year before at Sevestapol. Elsewhere, the front is shortened and divisions are freed up for the intended defense of Italy.
On 1 September 1943, Pravda issues an announcement that "Army Group Poltava" has ceased to exist, destroyed due to traitorous conduct by key members of the STAVKA. Of the 'convicted', Zhukov is the most important one to be named. He and the others are hanged in Red Square, and a massive stalement akin to the front in World War One settles across Russia. Germany has its breathing space: for now.
......
To be continued.