The most iconic images of the two battles. Both staged.
Though vastly different in time, place and circumstance, the battles of Gettysburg and Stalingrad share some interesting similarities.
Both were the culmination of invasions gone wrong. Both marked the strategic high water mark for their respective nations. Both were attacks by smaller, more powerful forces against larger armies, more poorly organized and led.
Although neither battle was decisive, in the sense of deciding the war, both represented a change in momentum that lasted the duration of the contest.
The preceding campaigns had ended in disaster for the battle's defenders, Case Blue in summer 1942 had cleared Southern Russia and cleared the way to the Caucasus, Chancellorsville in May 1863 was the Army of the Potomac's worst defeat.
These previous defeats set the psychological tone for the battles, leading to fatal overconfidence in the invaders. Lee had come to feel (IMHO), that his boys could defeat the North on any field at any time. The German high command, from Hitler on down, were certain the Red Army was on their last legs. Both were looking for a chance to pin the enemy in order to crush them. As a result, neither battle was planned in advance by either side.
The other notable psychological issue was that the attacker's overconfidence led them to discount the ability of the defending soldiers to withstand their assaults. They became contests between the high commands of one side, and the regular soldiers of the other. In both cases, the soldiers stood their ground and won.
On a tactical level, both attacking armies gave up inherent tactical advantages to press the assaults. This changed the nature of the combat, allowing the defenders to at least partially offset the attacker's superior mobility and firepower. The assaults themselves were numerous, and the failure of each to finish off the defenders was taken by commanders to indicate the defenders were weakened enough for the next assault to work. In neither case did the attacking commanders take a step back and contemplate alternative approaches despite the stated objections of their colleagues (most notably Longstreet, and von Richthofen).
But these parallels only go so far. Gettysburg was all Lee, Stalingrad was all Hitler. At Stalingrad, the German side had better equipment and an air force. At Gettysburg, the Army of the Potomac was better equipped, and had a cavalry. Lee's object was to
Meade was unsuited and unable to deliver a strategic counter-stroke. Had I Lee's army on the run, I would have been careful too. The Soviets, on the other hand, delivered a devastating counter-stroke, led by Vasilievsky. The Army of Northern Virginia got away. The German Sixth Army was destroyed.