What if the Ardennes Offensive did not occur?
There's a number of, 'what if' scenarios based on the Germans winning the Ardennes Offensive. I won't go into that here because it is a lengthy topic.
But what if Hitler listened to his top generals and did not launch "Wacht Am Rhein"? How would have that altered military history and world history as a result?
Here's my opinion.
1) Hitler listens to his generals and marshals his manpower reserves and last panzer reserves behind Germany's western borders, awaiting the late winter offensive of the Allies' 21st Army Group, 12th Group, and 6th Army Group.
2) Led by the brilliant Field Marshall Rundstedt, the Germans launch savage counterattacks up and down the Allies border penetration points. The Germans also employ well-situated and well-coordinated defensive strongpoints and fighting positions. The aggressiveness and savagery of the German resistance throws the Allies off-balance.
3) Rundstedt knows that British Field Marshal Bernard Montgomery has become overly cautious and yet wants his 12th Army Group to be in the forefront of the Allied advance. The Germans launch especially aggressive local counteroffensives against the 12th Army Group, relying on crushing hammer blows and hit-and-run tactics. Montgomery is convinced the bulk of the remaining German Army is arrayed against him and he halts the 12th Army Group ordering it to dig in. Montgomery demands Allied Supreme Commander Eisenhower dispatch American reinforcements and more supplies to the 12th Army Group, which Eisenhower ignores.
4) Rundstedt is aware the greatest danger comes from the aggressive, highly experienced Lieutenant General Patton and his Third Army, assigned to Lieutenant General Bradley's 21st Army Group. The 21st Army Group is where Rundstedt concentrates more resources to the defense. Buoyed on desperation, patriotism, and good leadership, the Germans manage to stall the Allies just past the German border. The Allies make short gains into Germany but cannot go further. The Western front becomes a vicious, bloody back-and-forth slugfest.
5) While the Germans manage to slow and halt the Allies tenuously, they cannot halt the Red Army juggernaut in the east. Stalin launches two Fronts amounting to two million men to capture Berlin and end the war. As in real history, the Soviets surround Berlin and at great cost in human lives capture the capital. Hitler commits suicide and Admiral Donitz becomes the next leader of Germany. The Soviets this around do not stop because the western Allies are bogged down near the Franco-Belgium-German border. 3/5ths of Germany remains unconquered. Soviet leader Josef Stalin orders the Red Army to push forward into the rest of Germany and meet up with the western Allies, catching the remaining German ground forces between them. Remaining German forces deep in Germany are unable to stem the Russian tide. Despite Admiral Donitz's acceptance of unconditional surrender, the Soviet Red Army continues its relentless advance.
6) The Allies and the Soviet Union accept Admiral Donitz's unconditional surrender but the Red Army continues its advance until it makes contact with the western front. The war is over in Europe. Hitler is dead. The western allies occupy only a small strip of German territory near the western border. The Red Army occupies almost all of Germany.
7) The western Allies demand that Josef Stalin honor the Yalta Conference agreements and withdraw the Red Army to its agreed-upon zone of occupation. A tense international standoff occurs as Josef Stalin contemplates his options.
a) Stalin can honor the Yalta agreements and withdraw the Red Army to its
agreed-upon zone of occupation around Berlin leading back to Poland.
But that means giving up huge territorial gains and Stalin's generals
and field marshals are adamantly against withdrawal.
b) Stalin can decide to keep the Red Army in place, insisting on altering
the Yalta agreements. Stalin knows this is extremely risky. This
entails very real military conflict against the Americans and British-
Canadians unless Stalin can convince their respective governments
otherwise. Stalin knows he will be resisted by British prime minister
Winston Churchill and the new American President Harry Truman, who is
not as accommodating to Stalin as the late President Roosevelt was.
Stalin's ambitions knows no bounds but he can be cautious when
confronted with powerful enemies. Stalin knows the Allies are war
weary, especially the British, who have reached economic exhaustion
and the end of their manpower reserves. The greatest danger is the
American military, at the height of its power, and empowered with
seemingly endless resources in men, supplies, and equipment. The
temptation is overwhelming. With all of Germany under Soviet control
the rest of western Europe will easily fall to the Red Army if he can
dispose of the British-Canadians, Americans, and reconstituted French
Army. While Stalin and his diplomats negotiate and bluster with
London and Washington, Stalin's STAVKA continues to match the current
and projected strength of the allies in Germany against the Red Army
should military confrontation become a reality. The clock ticks away.