Cavalry and chariots against infantry

[Domen]

The sources mention that missiles thrown against horses scared them.

I think it is more or less the same case like with what I wrote about Tatar horses according to Polish accounts (it can be found in the thread about Polish Hussars that Macedon compiled from this thread). Namely - that Tatar horses were not accustomed to gun fire, while European horses were - and that's why using firearms against swift Tatar cavalry was regarded as efficient (much more efficient than using them against, for example, Swedish cavalry).

I think the same is with this case - sources which you quote Macedon, mention reactions of horses not accustomed to large-scale usage of missiles against them.

Just like horses of Crimean Tatars were not accustomed to firearms in the 16th century (as firearms in this part of Europe - at the Black Sea and on the steppes - were not very common at that time). But horses can be "accustomed" or "trained" to ignore such things.

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Edit:

I guess that this is not the case for firearms, since the bullet would not be visible

Well - there are accounts which prove the opposite (see above). But horses could be accustomed to this (just like - most certainly - they could be also accustomed to the sight and noise of missiles).

Regarding the bullet being not visible - the bullet maybe not, but firearms at that time were using black gunpowder, which produces a lot of smoke with each shot - and this smoke is surely visible.

Also - firearms were very loud weapons, much louder than bows. And horses could hear that noise.

Missiles also produce some noise, not that much though - and they don't produce smoke.

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the bullet would not be visible (although I expect it to on average be more deadly).

If a bullet hits & penetrates into flesh - it is rather more deadly than an arrow (it also depends on the bullet's calibre though). But old firearms were inaccurate, slow to reload & fallible (technically unreliable).

Moreover - there are accounts, which say that horses are very resistant even to bullets:

A participant of WW1 wrote this about resistance of horses to fire of even modern firearms:

"The fear of infantry was intensified by great resistance of horses to wounds. During a charge only killed horses or those which had crushed leg bones were falling immediately. Other horses, often wounded several times, even mortally, in a zeal of attack continued to run and with their entire mass - under riders or without them - were blindly bumping into the enemy, parting and trampling his lines. From distance this apparent lack of casualties of the charging unit was creating an impression of inefficiency of infantry fire. Infantry was confused enough, that most of bullets were starting to fly too high, and often in a decisive moment infantrymen were throwing their weapons and starting to run away, which meant a certain annihilation for them."

Hence I wrote before, that the easiest way to stop a horse is to shatter its leg bones.

And in case if you doubt the reliability of this account (basing on the stereotype of cavalry being totally useless in WW1) - please take into account, that cavalry was totally useless only on the Western Front of WW1, where positional trench warfare and great saturation of modern weapons such as machine guns and modern artillery was present - while in South-Eastern theatres of WW1, as well as on its Eastern Front - which were both much more mobile frontlines than the Western Front - it was still extensively used (since mobile armored and motorized forces typical for WW2 did not exist yet).

There were also some successful "classical" cavalry charges in WW1 (despite the increasingly overwhelming firepower of infantry and its support weapons) - such as that carried out by the Australian Light Horse at Beersheba in 1917 (there is a movie which includes the scene of this charge):

http://www.youtube.com/watch?v=vvjE3h0Ahz8