Why didn't line infantry tactics try to keep up a constant volley of fire?

Those tactics were largely used in Europe, but not always in America (by the British). That's because most European battlefields were partly wooded or otherwise "obstructed," while American battlefields were often (not always) more open.

The problem was that a musket was a slow-loading, single shot weapon that could support only one shot at "killing" distance, before the enemy closed in with bayonets. Hence, the British practice in America was to have their troops fire one volley at 50 yards, and then charge in with bayonets; much as the Romans did by throwing "pilum," (throwing spears), then charging in with swords.

"Staggering" musket fire in this way would only have slowed down the bayonet charge, and also weakened the impact of a single volley in open ground. At the battle of Quebec, the British used single-shot/bayonet charge tactics, while the French used the tactics you described. The British won. Of course, in wooded ground such as around Saratoga, bayonet charges were largely ineffective, and it made more sense to "stagger" musket fire.

Question: Why didn't line infantry tactics try to keep up a constant volley of fire?

Short Answer:
It wasn't due to a lack of knowledge. From the mid sixteenth century until WWI volley fire was the predominant way infantry discharged their weapons on the battle field (groups of men trained to fire together). From early on in that period tactics to kept up a continuous or rolling volley of fire were well known to European armies. Many of the American Revolutionary leaders such as Generals Washington, Horatio Gates, James Clinton and others were experienced officers in the British Army prior to the American revolution and thus would have been aware of these techniques and how to train and command troops to utilize them to their maximum effect. Still the United States forces in the revolutionary war benefitted greatly after Baron von Steuben in 1777 introduced the most modern of these techniques known at the Prussian or Alternate method. It utilized specialized hardware like the ram rod and fewer rows or platoons of men with a condensed loading cycle to increase the rate of fire. Thus I think your question boils down to why weren't these continuous fire tactics used exclusively in battle for the 250 - 300 years while volley fire was in favor. And more specifically why wasn't it used more by the British and Americans during the American Revolution given the British were arguable the best trained and accomplished army of their day and given the Americans were aware and trained in these same techniques.

The answer to the former question is, continuous salvo's simple were not always superior. If you had six rows of men all coordinating their fire in order to keep up a constant rate of fire, (six rows were the norm of the two most regularly used constant fire systems early on); it limited overall rate of fire. Early on well trained musket men could shoot 1 or 2 times a minute ( 2 or 3 times under the Prussian Alternate Method taught by von Steuben to the Americans). Platooning them reduced the first volley to 1 sixth the number of total guns. Continuous fire had a psychological benefit but as far as getting as much lead down range as quickly as possible it was not optimal. In staggering you reduced your overall fire and overall concentrated fire was the game winner in most cases with muskets. This is because muskets were not accurate. Muskets were most effective when shot by many men in a volley and all at the same target at relatively close range. The more muskets firing the better.

What would put more lead down field fastest. 600 men all shooting at once.. reloading say twice over a minutes time and each time all shooting again.. Or 600 men shooting 100 at a time, shifting to the back six paces, as someone behind shifted forward, and then maybe as much as 10 seconds latter 100 more guys shooting. It would take you six volleys in order to match the devastation of the first volley of your enemy. Think of all the waste of the loaded muskets laying on the ground beside dead or wounded men after that first or second overwhelming volley they would endure!

Also after you received / endured your enemy's total volley, at relatively close range( because the musket wasn't useful at anything but short range (100 yards was it's maximum effective range, as mentioned by Tom earlier 50 yards distance was better and often favored)... next up was generally a bayonet charge, disrupting your third or fourth volleys.

For the American Revolution there were specific reasons continuous volleys tactics which both sides were aware of, were seldom used. First off because the British didn't believe the colonials were much of a threat and didn't deem it necessary to use their best tactics against a colonial opponent. The British opted for a more expedient tactic which brought them soonest into close range with the colonials. One volley, bayonet charge. The colonials did not have bayonets, and generally used irregular weapons. The colonials were also undisciplined. All of these properties put the colonials at a disadvantage when bayonets were used. Lastly the colonials had nearly no calvary to intercede or flank a bayonet charge. The abbreviated British tactics capitalized on all of these advantages.

After the revolutionary war, the Battle of New Orleans in the war of 1812, where the British lost more than 2000 men to the outnumbered Americans 13; demonstrated one liability of adopting a centrally commanded complex firing systems against an unchivalrous enemy. Officers can't give the important and complex firing commands if they're dead.

Detailed Answer:
There were many different techniques used to coordinate infantry fire. They were like hair or clothing styles. Different countries favored different techniques and their strengths and limitations were discussed and debated among professional soldiers from different countries. A commander would be aware of which technique his enemy favored and might favor an alternate technique to maximize the weaknesses of his enemies approach.

In the matchlock period their were primarily three methods for infantry to discharge their weapons. "The traditional Dutch method or "counter march" /continuous", "Swedish salvee / non continuous" and the “Swede’s way / also continuous”

"The traditional Dutch method" also called the counter march or caracole. Involved six rows which fired by row(rank). Each row would advance, fire and then retreat to the back to reload. Problem was this formation wasn't particularly good when retreating, or maintaining it's position. Also it wasn't good directing fire as it required some firing lanes be used for paths of retreating or advancing soldiers. So you had to be advancing and you had to be facing your target.

"the Swedish Salvee" also involved six ranks only the ranked doubled up into 3 lines, front middle and back. Then all three ranks fired at the same time into one devastating volley. Usually followed by a bayonet or pikemen's charge. This method was used extensively during the English Civil War (1642-1651). The obvious disadvantage was that all the muskets were discharged at the same time and left the troops vulnerable as they were reloading. The advantage was your enemy endured one massive total expenditure of your muskets, and thus it was efficient in that no loaded muskets were left unfired after the first salvo.

The Third Method was the "Swede's Way", oddly enough a variation of the Dutch method favored by the swedish general Gustavus Adolphus. It involved a line of musket men being deployed in a checkerboard layered manner, three deep. So each man had a clear path to the front. The first layer would fire and retire, followed by the second layer, and then as you would expect the third layer. The Battle of Breitenfeld, on September 17, 1631, saw this tactic being employed. In 1675 King Charles II’s added this method to the English Military Discipline. Advantages included clean lines of advance. It could be used moving forward, backwards or stationary. Disadvantages is it didn't mass fire particularly well given it required troops to be spread out in essentially one multi level line, and it had problems with directing fire other than straight forward.

Flint Locks By the end of the seventeenth century matchlocks went away and flint locks became the primary weapon. Pikemen previously used with musket men in a 2-1 ratio; went away in favor of more musket men with early plug bayonets. ( muskets could not be fired when the plug bayonet was used because it obfuscated the muzzles when deployed. )

So now people took the three previous method and innovated from them.

In 1708 the Duke of Marlboro innovated off of the Dutch system to create what we call today platoon fire. He separated his division into battalions and the battalions down to 18 platoons. Each platoon employed the dutch system but each platoon could be directed independently and placed strategically around the battle field to provide supporting fire or suppressing fire or compounding fire against an enemy position.

Advantages:

• very flexible and adaptable.
• high degree of control
• Platoon firing allowed the fire to be directed, if necessary, obliquely to the left or right and not just directly to the front of the battalion.
• enemy came under concentrated and continuous fire once the action opened
• One-third of a battalion would always be loaded and ready to deal with an emmergency.

Disadvantage: Very complicated to train and command.

In the mid 18th-century The "alternate system" became prominent. This was based upon new Prussian loading techniques which greatly improved the speed at which muskets were loaded. Both the British and Americans used this technique during the American Revolution, although not primarily. Baron von Steuben introduced this method to the American Army famously at valley forge and it greatly increased the colonials rate of fire. He wrote the first infantry training manual for the United States, called the "blue book" which remained in service through the war of 1812.

Overall though the British didn't use standard european volley fire techniques in the American Revolution. Several reasons:

• the preference for the bayonet against a skittish opponent
• the need to fight over broken terrain and extended frontage
• the lack of American cavalry, which did not require the British to reserve a portion of their fire at all times to deal with sudden emergencies—hence the preference for a single general volley immediately prior to the bayonet charge.

During the Battle of New Orleans and the War of 1812, Andrew Jackson's sharpshooters targeted British officers from the onset of the battle. The subsequent death of the commanding British officer and many of his intermediates left the British army, fresh off the battle fields of Europe where they had defeated Napoleon at a decided disadvantage. Over 2000 British soldiers died to 13 Americans in this miraculous victory against what was widely considered the finest army in the world. Sometimes too much central control and the flexibility that grants you is a liability.

Overall volley fire should have been abandoned with the advent of the Minie-Ball but it wasn't. The Minie-ball was a round which allowed riffles to be loaded as quickly as muskets. It was an oblong round with a hollow tail which expanded when it fired. The expansion allowed the round to pick up the riffled barrels and thus dramatically effected accuracy. The real innovation was though they expanding round allowed it to be smaller than traditional riffle rounds in diameter, which vastly improved loading speed. Prior to this riffles were slower to load because the round needed to be larger to pick up the barrel grooves. today's riffles and even riffled pistols utilize rounds larger in diameter than the barrels of the weapons which fire them. The powder forces the compaction of the round in order to pick up the riffled ridges in the barrel. It's also why rounds are made typically of softer medals like coper or lead. Anyway the Minie-ball which became prominent in the American Civil war and Crimean War, dramatically increased the lethality and range of infantryman which up to this point primarily used the fast loading but highly unaccurate muskets and only used the slower loading rifles for specialized troops like sharp shooters. Thus in the American Civil war volley fire by rows of men all lined up on the battle field, and the resulting counter fire were devastating.

Amazingly enough even with breach loaders and repeating riffles volley fire continued to be the primary way infantrymen fought up until WWI and the advent of the machine gun. With the advent of the machine gun massing troops for one strong volley or even continuous rolling fire was no longer just stupid, it was suicide. WWI is when volley fire finally slipped into the pages of history.

Sources:

• The Dutch Tactical System and the Thirty Years War
• Smooth Bore Musketry
• Pike and Shot Tactics
• Fire By Volley: European Musketry at War
• List of Military Leaders in the American Revolutionary War
• Volley Fire
• Remarkable Kentuckians: The Sharpshooter That Broke the British in New Orleans

This seems to be several different questions so I'll take each one in turn.

Why didn't line infantry tactics try to keep up a constant volley of fire?

I'm a little perplexed at the phrasing of the question because it implies that line infantry tactics did not "try to keep up a constant volley of fire". In fact linear infantry tactics were expressly developed to maximize the volume of fire (or conversely, as I'll briefly mention in a sec, to negate the advantage enjoyed by an enemy with a higher rate of fire). So, allowing for the basic reality that a constant stream of fire wouldn't become technically possible until the advent of repeating firearms, it is nonetheless the case that linear tactics did yield the closest thing to a "constant volley of fire" that 17th and 18th c. technology could achieve.

Often in movies on the American revolution and back when muskets were common place the opposing armies would line up facing each other and take turns firing. One side, then the other. Kind of like a volley.

While I'm not sure if this is historically accurate, brief research online says yes.

Movies may be good at capturing the individual soldier's perspective of a battle--friends who are combat veterans have singled out "Black Hawk Down" and "Thirteen Hours" to me for particular praise in that department--but for a variety of reasons the tactical context of engagements tends to be set aside by the producers. Without dwelling on that latter point, suffice it to say the essence of infantry tactics in early Modern Europe resides in the details of something that the description somewhat glosses over: the "lining up facing each other" part.

Had cameramen been on-site to record the collision of Frederick's Guards battalions with the Austrian infantry at Leuthen (1757), it at times might indeed have looked like two sides "lining up facing each other": the two sides would draw close and exchange volleys. But the means mustn't be confused with the tactics: Frederick the Great and his opponent, Prince Charles, weren't simply lining their men up for a duel to let fate decide the matter; they sought what every general of the era sought: set the stage so that when both sides "lined up facing each other", their own side would come off the better. And so it was that early Modern European tactics emphatically did not center around lining up one's men and letting them take turns blasting away. Just the opposite, actually.

In some cases, generals might try to rush the enemy and put him to flight before his firepower could tell. The French and the Russians, whose infantry in the late 17th and early 18th c. was often inexpertly handled, were notorious for this. Oftentimes it worked, but other times, not so much. There was one funny episode where the notoriously lethal Dutch musketeers gave the French Guards such a proper thumping that Louis XIV, embarrassed, tried to ban French infantry from engaging face-to-face with their Dutch rivals unless they had overwhelming numerical superiority. In other cases, generals might make a demonstration to the enemy's front while using some element either man-made (cavalry, e.g.) or natural (a hill or a depression in the ground, e.g.) to conceal the movement of another force around the flank. Commanders such as Turenne, Marlborough and Frederick made their names by winning battles in this way. All European armies also made extensive use of light infantry, whose job it was to conduct reconnaissance, harass the main bodies of infantry, provoke premature attacks, pick off drummers and officers with their specialized rifles, and so on. Perhaps the best known light infantry belonged to Austria, which raised them from the regions of the empire bordering the Turks (themselves no slouches at this style of warfare).

To return to Leuthen. The movie cameras might capture the dramatic bits of the battle, showing men a few dozen paces apart blasting away with muskets. What they would not show would be the implementation of tactical maneuvers: The initial Prussian feint that led Prince Charles to over-commit his forces, including all his best troops, to the wrong wing. Frederick's lucky (and probably unintentional) use of an unseen Austrian blind spot in their view of the battlefield from the village of Leuthen. The impeccable timing of the Prussians' artillery and heavy horse, which both did murderous work on Austrian forces once these had been fixed or pushed back by the infantry. And so on.

So what did the Austrians in at Leuthen was the success of the Prussians in using the enemy's dispositions against him, not the superiority of the Prussians in a firefight (though, as it happens, the Prussians' more rigorous training often gave them the upper hand in those exchanges).

From a more tactical standpoint why didn't one army just shoot, then have their first line duck and/or move behind the second line thus allowing the first line to reload and the second line to shoot with their already loaded weapons? In such a fashion that they would be hot-swapping empty shooters with loaded shooters and not having any quell in firing from their side. This always seemed like a point of contention for me.

This seems like a question apart from the first two, to me. And a more straightforward one. (Here I'll borrow heavily from an answer I also wrote on QUora.) As the most popular answer to this question says, the concept described here was implemented in Modern times first by the Dutch, and it was actually inspired by the Romans. In a letter from 1594 to Maurice of Nassau, the prince's cousin William Louis goes into detailed discussion of a tract he read by the Greek military writer Aelian. In it, Aelian describes a Roman system for missileers--slingers, javelin-throwers, etc.--who were organized into six ranks. The first rank would release their weapons, then step back while the next rank released theirs, who would in their turn step back and make way for the third rank, and so on. The enemy would thus be subjected to a nearly continuous hail of missiles, with no single row of slingers or javelin-throwers becoming too exhausted to keep launching. William Louis goes on to suggest the adoption of similar practice in the struggle against the Spanish.

The Dutch adopted the new system with considerable success, and when the Swedes hired Dutchmen to train their armies in the early 1600's, they adopted it too, with similarly good results. Improvements were made along the way, but in broad strokes, for over a century, deep formations of musketeers were the norm. The drill called for musketeers to advance either by files, ranks, or divisions, shoot their weapons, then retire while the next firing group took their place. In other words, the paradigm laid out in the question, where some men fire, then are replaced in the firing line by another group, thereby maintaining the enemy under a continuous stream of fire, was the default. It's worth pondering, at this juncture, just how suited such a concept is to battle, that is, to a situation in which one might find oneself staring down an oncoming horde of enemy horse or infantry. And it's a question that makes the point: the predominant form of combat throughout the 17th c. and well into the middle of the 18thc., was not open battle at all, but a different species of engagement altogether: siege warfare, which isn't as cool-looking so isn't made into movies very often. Keeping up a steady tempo of fire by ranks or divisions in the presence of the enemy is challenging and dangerous, but rather less so behind entrenchments and chevaux-de-frise.

Eventually, a combination of political events and technological innovations brought about new systems of firepower deployment. Infantry formations became wider and shallower, and (counter-intuitively perhaps) volume of fire increased as a result. But this is actually an entirely different question--how the linear tactics of the 18th c. evolved from the pike & shot squares of the 16th and early 17th c.--so I'll leave that for another answer.

Sources:

Arnold, Thomas. The Renaissance at War. London: HarperCollins, 2001.

Chandler, David. The Art of Warfare in the Age of Marlborough. New York: Sarpedon, 1994.

Childs, John. The Nine Years' War and the British Army, 1688-97 - The Operations in the Low Countries. Manchester: Manchester UP, 1991.

Duffy, Christopher. The Army of Frederick the Great, 2nd Ed. Chicago: The Emperor’s Press, 1996.

Szabo, Franz A. The Seven Years' War in Europe, 1756-1763. London: Routledge, 2008.

Oda Nobunaga mowed down the Takeda clan's cavalry this way at the Battle of Nagashino (1575). Here is a dramatization.

Nobunaga built a stockade and positioned three rows of arquebusiers behind it. The cavalry was unable to withstand the continuous fire of the rotating rows of gunners to break the formation.

That's roughly what they did. Both sides would line up their men, where the defender had the advantage: they could form two or more lines. The first line fired, then reloaded, while the second line fired, etc.

The attacker can't do that. The second row would be shooting their own men in the first row. But their advantage was the bayonet. Fire one volley with as many men as possible in the front row, then immediately follow up with a bayonet charge.

Handing over loaded guns happened, but more in sieges. The guards in Hougoumont did that during the battle of Waterloo. There wasn't room enough for all the guardsmen to fire their weapons.

I'm sure this was tried in exercises, but not done in the field as it is (very) impractical. Exchanging loaded/unloaded rifles under cover is one thing, doing the same without cover is highly dangerous.

That brings us to black powder weapons. Those guns are highly inaccurate. Most guns didn't have rifling or sights; there was no need for it. You fired your gun in the general direction of the enemy, and hoped for the best. You didn't aim your weapon at a particular enemy, you tried to hit the opposite battalion approaching. Next comes the rate of fire. One could should at best 2 or 3 shots in a minute.

That means that the approaching enemy had to endure one volley, or at worst 2 volleys and they were upon you. The best way to counter it was to have as many men fire as many guns at the same time. Reloading wasn't (most of the time) possible.

I write about guns not about rifles. Rifles existed, but they worked slightly different. Rapid massed fire was not feasible, but they were used for carefully aimed shots. The British had special units with rifles, such as the 95th. Those soldiers were elite units, and as such rare.

Rifles could of course be mass fired. The problem was the reloading. You can reload a musket in about 20-30 seconds, giving you a rate of 2-3 per minute. (That's under optimal conditions, at the beginning of a battle. At the end of a battle that rate is considerably lower.)

Rifles have rifling in the barrel to make the bullets spin. In order to do that, the bullet must fit really tight. A rifleman had to ram the bullet down the barrel with a mallet, literally. He'd be real good if he could fire one shot in less than a minute.

Your question is a good one; different answers were found by the British and the French. The French preferred the ordre mixte or mixed order. They found that the combination of line with column worked best for them. Most of the troops would be in an extended line formation, with columns on the wings. They used the firepower of the line, and the impetus of the columns. It was a much easier formation than deploying all your troops in an extended line. Raw troops could master this drill quickly. Later on, when the French men power well dried up that was the only practical drill they could perform. Attack columns got bigger and bigger and more unwieldy.

That was one of the disadvantages. The bigger an ordre mixte becomes, the less firepower it can have. If you double your formation of 1000 men with 400 soldiers capable of firing, you have 2000 men with perhaps 450-500 men capable of firing. A slight increase in numbers, but a huge drop in percentage.

The British used professional soldiers, not conscripts. More quality was expected, and they were much better drilled. The British preferred to use the extended line formation. This formation is far more complicated, but it gives the highest firepower. Maneuvering is really difficult, which is probably the reason why the Brits preferred static positions and cover.

The difficulty with the Ordre mixte was the lack of firepower. Only the front row and the two or three following rows could fire, plus the man on the outer edges. Not everybody. Deploy 1000 men in ordre mixte, at best 400 men can fire. Deploy them in an extended line, and all can fire. (But they can't maneuver worth a damn.)

So why use the ordre mixte? It's intimidating, to say the least. You have > 1000 men approaching you. Yelling "vive l'empereur!". The 'pas the charge' was played or 'le victoire et a nous', you can see huge mass of soldiers approaching armed with bayonets. You and your mates give a volley and they still come. That's intimidation on steroids.

Until you meet well drilled troops that have been trained to hold fire and repel that charge. Which the British did in Spain. Almost never an ordre mixte attack succeeded against the British. And it failed spectacularly at Waterloo.

• http://balagan.info/attack-column-or-ordre-mixte-how-did-the-french-deploy-at-albuera
• https://en.wikipedia.org/wiki/Line_(formation)