Vesicles, thanks for the information.
Here's my summary of Qin vs Alexander the Great . . .
I am going to choose a fair battle, which means the two sides have ZERO huge advantages in strategy, tactics, government, economy, technology, culture, religion, quantity, experience, training, and allies. If you argue about unfair battles, then the army with the most advantages obviously has the edge over the other army. I know the best army will pick a battle that completely favors itself, but, like I said, I am talking about a FAIR battle.
Qin army favored both melee and ranged units. The Qin army used lots of melee or lots of ranged units or a balanced mixture (~1:1 ratio) of melee and ranged units depending on the enemy. The Qin army favored using its ranged units whenever possible. The Qin army had a greater variety of bows and crossbows, superior arrows and bolts, and superior bows and crossbows than Alexander's army and other ancient European armies.
Both the Qin army and ancient European armies had a variety of melee weapons.
Alexander and most ancient European armies favored melee a lot more than ranged units. A typical army had 75% to 90% melee units with 25% to 10% ranged units.
In this fair battle with both sides having 100,000 soldiers, I think the Qin melee would be outnumbered by Alexander's melee, but the Qin ranged units would outnumber Alexander's ranged units. Then Qin army would PROBABLY have around 50,000 melee and around 50,000 ranged units, while the ancient European army would PROBABLY have 80,000 melee and 20,000 ranged units. The Qin melee would be significantly outnumbered, thus disadvantaged against the ancient European army, but the Qin army would have a huge advantage in ranged warfare. My conclusion: the Qin ranged units would have the training and technology to significantly weaken and shrink Alexander's melee and ranged units, then the Qin army would send in its melee units for the finishing attack.
I know battles are rarely typical and fair, but I don't want to deal with realistic/unfair details, because anything could happen in realistic/unfair battles (i.e., 50,000 men in Alexander's army vs. 200,000 men in the Qin army, or the Qin army making a exhausting travel from East Asia, Central Asia, and the Middle East to attack Alexander's waiting army, or Alexander's army attacking the Qin army during the Qin Dynasty's downfall, or the Qin army attacking Alexander's army during Alexander's downfall). If you want to be very realistic, then you can't argue about Qin vs. Alexander the Great, because it NEVER happened. They were too far from each other. I am only dealing with a simple, fair hypothetical situation.
I based my opinion on various books on the Qin army, ancient Chinese militaries, Alexander the Great, and ancient European armies.
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This isn't about ancient China, Alexander the Great, or ancient Europe, but it's an interesting battle and I don't know where to put it.
The Battle of Nicopolis in 1396 AD is an interesting medieval battle involving European forces and the Ottoman Empire. The battle is interesting because of multiple reasons or because of the unpredictablity of warfare.
1. Some historical accounts were very unreliable about the size of the opposing sides. Writers from Team A wrote that Team A was greatly outnumbered by Team B, which is why Team A lost. Writers from Team B wrote that Team B was greatly outnumbered, and still came out victorious. This was only one example out of many of medieval writers exaggerating the size of armies. The writers lied for various motives: they decided it was better to state a number rather than admit their lack of knowledge, they wanted to make their own army look better whether in victory or defeat, and they wanted to make things look greater than reality (drama).
2. The warring factions were not just fighting against each other, but other enemies. The Crusaders were waging war against non-Christian Europeans and against Middle Easterners independet of the Ottoman Empire. The Ottoman Empire was waging war against non-Muslim Middle-Easterners and other Muslism civilizations. King Timur even got into the mix. In a way, everything seemed unpredictable.
Timur successfully attacked the Persian Empire and the Ottoman Empire. Timur built a dam to cut off the water supply of the Ottoman Empire's army, then Timur primarily used mounted archers with good feints combined with hit-and-run. The mounted archers were backed by mounted melee. Timur lead a decisive victory over the Ottoman Empire's army. The Ottoman Empire was devastated, and had to minimize their attacks on Europe, because of this major loss, the capture of the Ottoman Empire's Sultan by Timur, and the later ravaging of the Ottoman Empire by Timur's victorious army. Timur seemed to avoid going after the area currently called Saudi Arabia and Egypt, because Timur wasn't mobile enough. Timur had a highly mobile army, but his army still had limitations.
Timur then decided to conquer China (China had , but he met unexpectedly difficult weathers, and died during the trip. After Timur's death, his army and empire was never the same again.
3. The European army and the Ottoman Empire army made major blunders that cost them many men. The European army made a single blunder that cost them the entire war (IMO). The European army chased retreating Ottoman Empire soldiers up a hill without properly scouting or pacing themselves, and were suprised, then devastated by a counter-attack from hidden soldiers of the Ottoman Empire. I noticed this is a recurring theme in history for all civilizations. If an army is winning or fighting to a draw, the army could suddenly make a major mistake or suddenly fail to defeat a counter-attack, and lose the whole war.
4. Both sides used melee as the primary weapon, and ranged weapons as a secondary option. For ranged warfare, the European army used crude cannons and archers, and the Ottoman Empire's army used archers. The ranged units on both sides were successful in injuring or killing significant numbers of enemy units. However, the ranged units were only used to soften the enemy. The melee units were the focus and main means to defeat the enemy. The best melee units were mounted. Both sides had a lot more melee units than ranged units according to my best estimates from various sources.
5. Both sides were completely vicious towards prisoners of war, but they were also kind to a few prisoners of war. One moment an army is torturing, humiliating, and slaughtering prisoners, and the next moment the army is releasing the prisoners and helping them return home.
6. The European army focused more on offense, while the Ottoman Empire's army focused more on defense. Both sides pretty much went right at each other: encirclements were mostly tactical as oppose to strategic, and charges and retreats were more like all-or-nothing tactics and strategies, as oppose to repeated usage of tactical retreats and strategic retreats to test the enemy, gradually gain advantages, and to slowly, but safely win the war.
7. Even though the Ottoman Empire won this battle, both sides suffered large casualties. The Ottoman Empire was facing threats from multiple directions against multiple enemies, especially Timur's army. The battle didn't strengthen the Europeans or the Ottoman Empire. So much effort into something trivial.
8. When both armies returned home, they were robbed by the locals they met along the way. I don't know how true this is, because I thought the armies had noble and military ranks, which protected them against locals. The armies still had weapons. Maybe they were too tired and outnumbered to protect against criminals and peasants desperate for wealth.