2. Bows also were poor against heavy armor, even longbows. If you examine the oft-quoted battles where longbows were used heavily to good effect, knights were typically defeated by a number of factors, most prominently charging over bad cavalry terrain and having their lighter-armored horses shot at leisure from the flanks. Even so, the knights were often still described as being actually killed by men-at-arms in melee. Conclusion: The cavalry charge was defeated by longbows, terrain and stakes, the armour not so much. ("Idiot commanders" also comes to mind, but knights could be notably difficult to command reliably as it were.)
Battles that simply involved knights and infantry with longbows but without extensive terrain choice and preparation (muddy fields, stakes, ditches) on the part of the defenders tellingly resulted in massacre on the longbows end and virtually no losses by the knights. (See battle of Patay for instance, 1500 cavalry vs 5000 infantry mostly composed of longbowmen. Infantry losses 2500, cavalry losses 100.) You just don't hear about those battles quite so much in english-speaking culture for some reason. Hmm!
Erm... A french army consisting of sooooo many knights, far outnumbering the English knights (and the peasants they brought along)... And they killed them all with longbows and knives.
Herp derp derp herp derp.
No, they killed them with swords, the mauls they used to hammer stakes into the ground, spears, warhammers, swords, axes, knives, rocks, mud,
and longbows (which were only indirectly responsible for that horrid massacre). Plus the french knights at Agincourt behaved exactly how you'd expect impetuous cavalrymen to. The defeat at Agincourt was a hideous tactical error on a battlefield that didn't favor French cavalry tactics at all.
The french knights and men-at-arms attacked the English lines on foot after they got bogged down, slogged through the mud in heavy armor, and by the time they got there were so tired out from longbow impacts and footslogging that a child with a big stick could have taken them down.