Battle of Cedar Creek (1864), American Civil War. The Union forces were surprised and driven from their camps by Early’s Confederate Army, which did not follow upon their attack. Union General Sheridan came up and with other officers reorganized the Union forces and counterattacked, driving the Confederates from the battlefield.
I was down to 3 armies and just the two territories of Australia against 4 computer players, cashed in a set of cards, and pushed out and eventually won the game!
I love Risk!
I nominate the South at Chancellorsville. The South was outnumbered two to one and any sort of reasonable military tactics would have ended the war. Stonewall Jackson pulled out a miracle with his flanking maneuver which ultimately cost him his life.
Were it not for the Union incompetence, Gettysburg never happens.
Waterloo was, for Wellington at least, a damn close run thing. The British cavalry had been beaten into the ground over the course of the day, French cavalry was essentially unchecked beyond the immediate range of British musket fire, and the British infantry was trapped in square to fend off the same. The Prussians arrived under Blücher just as the French infantry was gaining the upper hand, pushing the advantage back to the coalition just in the nick of time and only then ensuring Napoleon’s defeat.
Washington crossing the Delaware probably is a contender. The Continental army was in pretty bad straits and morale was low. They needed the raid to be successful, not only for the supplies, but to raise morale to the point where soldiers would be willing to re-enlist.
AIUI, the battle was more or less a draw, because the Norman archers were just foiled by the Saxons using shields to block the arrows, and the Norman cavalry charges were useless, until near the end of the battle, when the Normans did a well-timed attack in which both arrows and cavalry converged on the Saxons almost simultaneously. That crashed the Saxon defenses.
In the early 7th century, the Sassanid Persians had overrun Byzantine Syria, Egypt and most of Anatolia and were besieging Constantinople. Emperor Heraclius managed a counter-invasion that lead to the disintegration of the Sassanid Empire (to the ultimate benefit of the Muslims, but that doesn’t detract from his achievement).
Alfred the Great, at his low point, controlled no more than an improvised fort in the Somerset marshes; he was to mount a comeback, drive out the Danes and expand his kingdom.
Robert the Bruce, following the failure of his first attempt to take control of Scotland, controlled no territory at all and was being hunted through the heather with a handful of followers. He was able to rally support for a second attempt and ultimately defeat both the English and his Scottish rivals.
In the 20th century, you have the Miracle on the Vistula, when the Poles defeated the Red Army at the gates of Warsaw.
There’s some debate about Harold’s death. The first account talking about taking an arrow in the eye was 14 years later. He is pictured taking an arrow in the eye on the Bayeaux Tapestry. Not all accounts mention the arrow. Some say that the claim Harold was felled by an arrow fired by William was an example of winner’s writing history. [Cite]
1066 was a bad year to be near arrows for people named Harold claiming the English throne. 
There’s some other claims that Harold Godwinson was killed by Norman knights in hand to hand combat either before or after being wounded. There’s even some claims he survived, heavily wounded, and went into hiding. Even if the arrow is accurate it would be hard to tell if that was the major turning point or just something that happened as the Saxon defense was already breaking/broken under the decisive Norman attack.
In any case, it’s probably a stretch to say the Saxons were winning tactically at any point. Tactically they were holding in what was probably better described as a stalemate. That was all Harold needed for a strategic victory. He held the throne and could call for more troops and supplies. William needed to defeat Harold tactically. Harold just needed to engage and not lose badly at the tactical level. Tactically what we probably saw was a shift from an early stalemate to a decisive Norman victory. It’s not till we expand the scope to the strategic level that the Saxons were ever winning.
It was the method of evacuation. They were going down in defeat trying to evacuate with naval ships which were easy targets that clogged up the shoreline when sunk. There was no plan B. They didn’t have any airplanes capable of loitering over the battle area to protect the ships. Had the Mosquito been available they would have had the ability to defend the ships.
Churchill became PM on May 10th and he pulled the small boat evacuation out of thin air. It was launched May 26th with 800+ civilian boats. 16 days later. Think about that. They were going to lose the bulk of their entire army.
The OT is full of miraculous victories. Some examples:
Hezekiah’s victory over the Assyrians. The Assyrians were a pretty major force and the people of Judah were holed up in fortified towns waiting for the inevitable. Then Yahweh did some smiting and that was it. The Assyrians went home.
Then there was Asa’s victory over an Ethiopian army with one million men and 300 chariots. Compare to the largest battle of the Napoleonic wars: Leipzig with less than 400k total for both sides.
Wasn’t there some siege or battle where the camp of the opponents of Judah got plagued with hemorrhoids?
Are these battles generally accepted as having occurred by a consensus of historians and archaeologists? Much less on the scale claimed?
Because, I mean, the rebellion’s victory over the Empire (which is also purported to have occurred a long time ago) at Endor was a pretty stunning comeback.
The Asa stuff is clearly made up. There may have been some minor battles involving him but it’s not clear who they tangled with in this case (and it probably wasn’t Ethiopians).
The Hezekiah tale has some historical basis. What we know: Sennacherib (after taking down the Kingdom of Israel) went after Judah. The attack went as far as besieging Jerusalem.
Afterwards, Hezekiah agreed to a tribute and the Assyrians went home.
We just aren’t sure what happened inbetween. Something convinced Sennacherib to take the money and run. The Assyrians don’t say why which might imply things didn’t go as intended. The Bible says divine intervention. Some conjecture a disease broke out in the Assyrian camp.
But Judah got to hand around for a while longer. Then Nebuchadnezzar showed up and had no problem successfully besieging Jerusalem.
The Battle of Warsaw, 1920, in the Polish-Soviet war. The Polish army, collapsing and retreating, managed a brazen counterattack with an army that didn’t even have enough boots to go around, driving the Soviets from the field and claiming at least 65,000 prisoners.
It lead to major cult of personality being built around the general, Józef Piłsudski, and arrested the westward spread of the nacent Communist movement.
The Wikipedia article does it a lot more justice than I could hope to.
Syria may have come within a whisker of pushing Israel off the Golan Heights, which (as already noted) Israel took in the Six-Day War of 1967. And Egypt pushed Israeli forces a good ways back across the Sinai peninsula, also won by Israel in 1967. But Israel’s control of Israel proper was never threatened in the Yom Kippur War; the Sinai and the Golan Heights did their job as buffers.
True.
The West Bank was not involved in the Yom Kippur War. Israel took the West Bank from Jordan in 1967, but Jordan did not participate in the Yom Kippur War.
It may be overhyped, but I think a case can be made (and is made) that without the tactics (and heroics) of Joshua Chamberlain and his 20th Maine, Gettysburg might well have turned out to be a Union defeat.