As someone who enjoys reading books about history, particularly military history, I am familiar with the speculation that some people like to make about how history would have turned out differently if the positions of the winners and losers in various battles were switched. Among the prominent examples are "What if Napoleon had won at Waterloo?" or "What if Lee had won Gettysburg?"
The idea for this post came to my mind recently when I was reading some reviews on Amazon.com for a book that came out late last year called "The Siege of Vienna", which recounts the attempt by the Ottoman Turks to take the city of Vienna in the year 1683. The Turkish defeat is often represented as the beginning of the decline of the Ottoman Empire. One reviewer on Amazon.com even posits that if the Turks had succeeded in capturing Vienna, "there well might have been no Christian Europe to dominate the world stage for the next 500 years."
Such viewpoints are mistaken in both the micro and macro level because they fail to take into consideration the realities that existed at the time. Pretend for a moment that the Turkish army managed to capture Vienna before the arrival of the Polish relief army under John Sobieski. Would the Turks have been able to hold the city? Looking at a map of the Ottoman Empire at its zenith, one can see how far Vienna is from the Ottoman capital at Istanbul. The Turkish army would have had to maintain an incredibly long supply line to keep its soldiers equipped with arms, ammunition, food, and clothing. And much of the territory through which this supply line had to run were conquered Christian peoples such as the Hungarians, whose loyalty was ever in doubt. So while the Ottoman army would have had to maintain itself far from its center of power, the armies of its enemies, including the Hapsburgs and the Poles, were close to their centers of power. Thus, the capture of Vienna would not have opened up the rest of Europe to Ottoman conquest.
What we also know from the study of history, is that at the macro level, the balance of power between Christian Europe and the Ottoman Empire had been slowly shifting away from the Ottomans for some time prior to the siege of Vienna. Nearly twenty years earlier, the first portent that the Ottomans were falling behind Europe militarily was felt. The Ottomans were facing off against their traditional enemies, the Austrians, at a place called St. Gotthard in 1664. The Austrians were reinforced by a contingent of French soldiers sent to them by Louis XIV. At the time, the French were the most advanced nation in Europe in terms of military techniques. Lord Kinross, in his well written book "The Ottoman Centuries", describes how when the Turks first saw the French auxiliaries on the battlefield, with their shaven chins and powdered wigs, they laughed at the French scornfully. But the French would have the last laugh as they ended up driving back the Sultan's Janissaries in disarray.
So, would history have turned out differently if the Ottomans had taken Vienna? Probably not, because the capture of the city likely would have done nothing to change the fact that the major powers of Christian Europe were beginning to surpass the Ottomans in terms of military technology. It is doubtful that the Turks could have held the city for long against a determined effort by the Christian powers to retake it. What the Ottoman defeat at Vienna made apparent to its enemies was that it exposed the weakness of the Turks and emboldened them to annex its European territories.
As I mentioned above, another popular speculation is how the American Civil War might have turned out if Robert E. Lee had won at Gettysburg. If the Union Army had been defeated, could Lee have taken Washington and won the war? Such an alternate outcome hinges on what kind of "win" Lee could have achieved. For Lee to have taken Washington, it would have been necessary not just to drive the Army of the Potomac from the battle field. Lee would have had to have destroyed the Army of the Potomac as an effective fighting force. To put this in perspective, Lee had won numerous victories against the Union Army during the thirteen months prior to the Battle of Gettysburg. In May of 1862, Lee drove back George McClellan from the outskirts of Richmond, the Confederate capital. He then decisively repulsed Union armies at Second Manassas, Fredericksburg and Chancellorsville. But the Union armies he defeated did not dissolve into a mindless rabble. The Yankees remained intact and licked their wounds to fight another day.
If Lee could not destroy the Union army when they attacked him, he was at an even greater disadvantage at Gettysburg, where he was attacking them. Most military historians would probably agree that the decisive day at Gettysburg was the second day, on July 2. On that day, much went wrong for the Confederate army as its Corps commanders tried to coordinate Lee's plan to assault both flanks of the Union army, while so much went right for the usually hapless Army of the Potomac. Still, if the Confederates had caught a few lucky breaks, particularly in their assaults on the Union left at Little Round Top, the Army of the Potomac might have found itself in an untenable position and would have had to retreat. But even so, it still would have been an intact fighting force posing a threat to Lee if he decided to march on Washington.
The most famous event of Gettysburg, "Pickett's Charge", happened on the third day. I put Pickett's Charge in quotes, because General Pickett did not lead the charge that day. His was one of three divisions that took part in the attack that was overseen by Lee's most reliable corps commander, James Longstreet. The famous charge was preceded by the largest Confederate artillery barrage of the war, which ironically did very little damage to the Union defenders. As even the most casual of Civil War buffs knows, the Confederate attack barely pierced the Union center before collapsing.
But suppose the attack had succeeded in driving back the Union Army? The Confederate cannonade that preceded the attack had depleted most of Lee's artillery supply. If he tried to march on Washington, not only would his supply of artillery been inadequate, his march on the capital would have been slowed by the need to transport the thousands of his soldiers wounded in the three days of the battle while trying to keep his army supplied in hostile territory. Therefore, even a victory for Lee at Gettysburg need not necessarily have resulted in the Confederacy winning the Civil War. Another possible alternative outcome for Lee, which I have not read, is explored by Newt Gingrich and William Forschten.
Likewise, Lee's defeat at Gettysburg, while an important victory for the Union, is not necessarily the turning point in the war that it is popularly thought to be. The war did drag on nearly two years more. It should also be noted that a year after Gettysburg, a smaller Confederate force under Jubal Early raided to the outskirts of a thinly defended Washington, D.C. while Grant was besieging Lee at Richmond and Petersburg. In the end, the outcome of the Civil War was not determined by Lee and Grant in Virginia, but in the collapse of the Confederate Army of Tennesse in late 1864, which paved the way for Sherman's famous March to the Sea.