The thing about archery is that it takes years to develop a high level of proficiency and build the muscles/form to effectively shoot on-target at distance with a bow that's got a draw weight in excess of 100 lbs. The English used to joke that you didn't train archers, you grew them. Edward III actually passed the Archery Law in 1363 which made practice compulsory after church and on holidays; there was even a rider in there forbidding other physical sports for men, because the time would be better spent practicing archery. However, I have no idea how widely or strictly that ruling was enforced.

On the other hand, you can teach somebody to shoot a gun in an afternoon. With a few weeks of instruction, most people can be trained up to an acceptable standard. That's a huge advantage when you're trying to conscript or enlist a large fighting force in a relatively short amount of time.

Couple all that with /u/ArkGuardian's spot-on assessment of how much more energy a musket can provide over a bow at any given range, and the reasons for dropping archers start to become pretty apparent.

As far as the English longbow goes, it was officially dropped by the English army in 1595, one of the last nations in western Europe to do so. At the time, many still considered the bow to be their national weapon so the move was fairly controversial and a great deal of military literature was written discussing the relative merits of each weapon. Contrary to many modern claims the majority actually did consider firearms to be better overall, primarily focusing on guns' far superior range and force compared to arrows, the fact that archers get less effective as they grow tired or get insufficient food and rest, or the fact that guns can be more easily used from behind cover/in dense formations.

One of the most damning pamphlets came from an English mercenary named Humfrey Barwick, who originally spent his youth training to be a good shot with a longbow before being given an arquebus when he first joined the army in the mid 1500s. He considered the bow to be a completely inferior weapon in just about every respect: anyone with an arquebus and good powder could shoot a bullet farther and with more force than the strongest archer, the gun is more accurate because it is aimed "by rule" while the bow is aimed "by guess", he even argued that firearms had a greater overall rate of fire because they could shoot from farther off or shoot multiple projectiles per shot ("A perfect Harquebu∣zere wil discharge more Bullets, be the time short or long, then any Bowman can doo arrowes"). He follows this up by claiming that in his long career as a mercenary he had seen hundreds of men killed by bullets for every one killed outright by arrows or crossbow bolts.

Similar arguments were put forward by well known war veterans such as Barnabe Rich and Sir Roger Williams (the latter of whom called bowmen "the worst shot used these days") and in the end the hardliners won out. The declaration that longbows were no longer fit to be weapons of war meant that even the "moderates", who agreed firearms were better overall but thought smaller numbers of bowmen might still be effective as light infantry or for shooting over the heads of musketeers and pikemen, were no longer being taken very seriously.

As for armor, during this period pikemen and cavalry still usually wore metal armor and longbowmen were still ordered to wear padded jacks, but arquebusiers and musketeers weren't ordered to wear any armor at all except for a morion. Those who claimed that 500 musketeers would beat 1000 archers in a straight up fight would have been aware of that fact.

This question's been asked quite a few times - search for "bows muskets" and you'll find plenty of threads. The best two I came across are this one, this one and this one (which also includes a link to the topic in the FAQ).

Interestingly, there's no complete consensus on the issue, at least in the transitional period (mainly 16th century).

Hiya!! Bear with me as I am not at home and will only be able to provide sources/detailed follow up at the earliest this evening. I've heard this kind of question come up before, but in truth it loses a lot of context about the early modern transition, the impact of gunpowder, and the military revolution. Particularly, it ends up being a one to one comparison between a skilled archer and a conscripted musketeer, ignoring the economics and politics of the time.

The "old school" or original theory centered on the idea that medieval cavalry was utterly ineffective, replaced completely by dismounted men at arms and pikemen in the later medieval period and incredibly vulnerable to archers. A further simplification along these lines was that firearms were adopted to pierce armor and became the new standard of projectile warfare. The example for this is often the Battle of Castellon where the English under John Talbot charged a fixed French position and were torn apart by rows of guns set up by the royal master of artillery, Jean Bureau. Another oft cited fact is that peasant archers overcame stunning odds to defeat the arcane feudal knights of France at Agincourt.

These tend to be, in my opinion, simplifications of a slightly dated argument combined with a a strong dose of popular history/bias. The English and French at Agincourt were using fairly professional soldiers, the English had a fixed position with cohesive command under Henry V, while France was completely disoriented by a mad king and a civil war (and most likely did not greatly outnumber the English). Similarly Castillon was a blunder, where the English commander misread the French and made an unsupported attack on Bureau's position. In truth both of these are fairly unique, though very important examples. However, I would argue there is far more going on here that is important to break down.

First while medieval warfare was uncoordinated and disordered by almost any measure, there were changes and transitions occurring. Overall, I would argue the primary transition coming out of the Middle Ages to the early modern period was the movement towards an integrated arms approach to warfare, that is using projectiles, infantry, and cavalry in concert. Again this is messy, but what we see is not a definitive superiority of one kind of troop or weapon, but the importance of effectively organizing multiple kinds of troops. Falkirk, the Golden Spurs, Patay, Formigny and other battles attest not to the inferiority of cavalry or the superiority of archery, but the risks of utilizing unsupported soldiers in battle. But you can also see this idea in the English Wars of the Roses and the Italian Wars which bridge this transition to the early modern period, where armies use combinations of troops: cavalry, pike, men at arms, archers, crossbowmen, etc. and use them in a combined fashion.

The second important thing to remember is the nature of the transition to gunpowder arms. While muskets and arquebusiers are now generally considered the crucial part, compared directly to more modern infantry weapons, that was not the original importance of gunpowder weapons. Engagements like Castillon were rare, but the French artillery's true contribution can be seen in the Normandy and Loire campaigns, where fortifications were incredibly vulnerable to Jean Bureau's artillery. This was incredibly important militarily but also politically. Medieval warfare and been heavily characterized by sieges and raids; battles were rare and seen as risky. More importantly a minor political actor with a formidable castle could stymie great lords and kings. But artillery rendered this moot, a king who was rich enough to invest in a sophisticated artillery train could render many fortifications moot, and only the richest could afford the more advanced fortifications to withstand artillery bombardment. This change can be seen two ways. First, the terror which the French army inspired at the onset of the Italian wars, an army with Swiss pikemen, cavalry, crossbowmen and the arguably the most advanced artillery units in Europe, which all of a sudden let the French move easily from city to city in Italy. Second, armies began to scale. Sitting behind castle walls was not feasible anymore, allowing kings to centralize authority in their kingdoms and scale their armies. All of sudden, the French could march twenty thousand men into Italy because King Charles VIII thought he was king of Naples, whereas they had struggled to that number a century before for the defense of their kingdom. The armies of the Wars of the Roses were huge compared to any previous conflict as well.

I realize you may be thinking I am rambling, but I promise this stuff is important :) All of a sudden you have larger armies and you need to arm them. Sure, some can be pike or cavalry, but the nature of warfare dictates they need some projectile support. So what do you do?

This is in truth where firearms began to become important. These larger armies need to more effectively arm large numbers of people. The English could raise a few thousand archers at their limits. This was a skilled trade by most accounts, and required specific equipment. You need feathers for the tail, arrowheads for the point, and fairly uniform assembly into the arrow itself. Was the effectiveness better than a arquebusier or musket? Possibly. But the firearms, by comparison, are effective enough to work in battle and far cheaper to mass produce in terms of the weapon and ammunition.

And I would argue that is the real kicker, maybe it's not definitively better than the longbow, but it's close enough. By the time we are talking Napoleon and levee en masse, it really wouldn't make sense to try to arm a few thousand specialized archers when they will be run down by tens of thousands of men with muskets and bayonets. So keep this context in mind when trying to evaluate rate of fire and power. Sure that stuff is important, but remember logistics, tactics and strategy are key too. Let me know if you have any follow up and I will try to get to it in a reasonable amount of time!!

As others have stated, it takes an entire childhood and adolescence to train an archer, building their muscles and marksmanship to a degree which would allow them to put eighteen arrows per minute down-range and expect them to hit anything. One thing I found interesting, however, was your citing of the American Civil War and other Napoleonic-esque wars as situations where archers would be useful, as there is a dimension here which is not often discussed (in my experience) which applies to both very well and is a major reason archery fell out of use, and that is disease.

Disease was by far the biggest killer in the American Civil War, killing (if I remember correctly) something like three to five soldiers for every one killed in battle. Regiments often had dozens if not hundreds of men sick and bedridden in hospitals with everything from simple flus to typhoid, tuberculosis, measles, and smallpox. However, it's important to remember here that diseases don't just immediately kill someone, they last over a long period of time, often ebbing and waning in their severity, but always having some impact on a soldier's health and ability to carry out his duty. And when you have a disease, if you're an archer, a skill which takes immense and continued physical strain to be able to keep up at an effective and quick pace, a disease or illness is much more devastating than to a rifleman, who only has to worry about exercising (at the risk of sounding a bit too simple) his legs (to walk) and shoulders/upper arms (to load).

Picture it this way. Say you're an archer of the English variety, equipped with an 80lb draw weight bow. Say you've got something relatively 'minor', a deep chest cough and a fever, which isn't severe enough (or at least not considered severe enough) to take you out of the battle and leave you bedridden in a hospital, but still will have an impact. Say you go into battle - the fever will make you dizzy after long marches in the (famously) hot Virginia/Maryland/Pennsylvania/Tennessee summers, and when you get into firing range, when you hold your breath and draw your bow, chances are if you attempt to fire 18 arrows a minute, due to the strain around your chest from flexing your arms and back and adjusting your breathing to steady your aim, you'll start sputtering and coughing like mad and won't be able to keep up your fire/your shots will miss. To compensate, you'll have to reduce your rate of fire to make sure your shots count, particularly if you're still dizzy.

Now compare it to a rifleman. Holding and steadying your rifle, which at most weighs something like 10-12lbs and requires nowhere near as much continuous, quick, intense strain on the muscles surrounding the chest and lungs, will be able to aim and fire with almost the same level of accuracy given he only has to do it three to four times a minute. The dizziness wouldn't impact him as much because by his very nature his rate of fire is slower - and even if it does, as you said, soldiers in these time periods weren't particularly good shots, even if they had the more reliable rifled muskets as opposed to the inaccurate smoothbore ones. The smoke and the subtle quakes of the body could often throw off aim.