Not to discourage other responses, but this thread discusses whether Europeans were brought over to help command American troops, and this thread discusses what, if any, impact the war had on military leadership in WWI.
According to C.J. Chivers' The Gun, it was the first time a rapid fire gun was used in combat situations. The Gatling Gun did not have a significant tactical or strategic impact on the outcome of the American Civil War, but it was a subtle hint to European powers that war was changing.
While Europeans were certainly watching the American Civil War, there were plenty of contemporary European Continental wars that were having a much more immediate impact on European war-making. The hugely influential Franco-Prussian War took place five years after the American Civil War, from 1870-1871, and in my humble opinion, was far more influential in bringing about modern warfare than the American Civil War.
I can't speak to tactics in general, but I can speak to the standard infantry small arm; in that realm, the American Civil War did not affect European military thinking.
The standard weapon of the Union was the 1861 Springfield. The Springfield was a muzzle-loading rifle that fired a .58 caliber, round nose, hollow-based conical bullet, and it used percussion caps to ignite the main powder charge.
It was, in every way, technologically equal to the service rifles that had become standard throughout Europe about a decade earlier. A few European countries, most notably Prussia, had already taken the next technological step: adapting a breech-loading rifle as their standard arm.
There was, however, one area where the American Civil War saw a major technological advance: the usage of a not-insignificant number of repeating rifles that could hold multiple self-contained metallic cartridges within an internal magazine, specifically, the Spencer and Henry lever action rifles.
Both rifles offered a vastly increased rate of fire compared to muzzle-loaders, and yet they still remained reliable for battlefield usage. Their ammunition also had a massive advantage over previous ammunition, as the self-contained metallic cartridge is vastly more reliable in damp conditions than a paper cartridge (or loose gunpowder). Though they suffered a decrease in range compared to a muzzle loading rifle, they were vastly more effective at short range.
In the years immediately after the Civil War, the armies of the world were looking to replace their muzzle-loading rifles. However, no major country adopted a magazine fed rifle for the standard arm, instead choosing to adopt single-shot breech-loaders. France, in fact, in 1866 adopted a new breech-loading rifle (the Chassepot) and did not even bother to use metallic cartridges. It would not be until the 1880's that magazine-fed rifles became the standard arm across the world.
The secopnd thread /u/Tsaihi links provides a pretty concrete answer. It didn't. At least not in any meaningful way.
A very good source is JFC Fuller's Generalship of Ulysses S. Grant. It covers some of the tactics and technology used in the Civil war.
There are a multitude of reasons why, but at the end of the day, there were very few lessons from the American Civil war that European generals either (a) hadn't already learned, or (b) didn't think were worth learning. Some of this was old world snobbery. Remember, at the beginning of the civil war America had only been independent 85 years and had only been organized as a country about 70 years, it was mostly agricultural, and was seen as a backwater to much of Europe. The American military was largely amateur, compared to professional Armies in Europe, and its armies were dwarfed by those of the continental European powers.
On the other hand, the Crimean War of 1853-56, involved many of the same lessons for England and Russia that the Union and Confederacy learned about troop movement by railroad and the power of new artillery pieces with rifled barrels and explosive shells. See Royle, Trevor (2000). Crimea: The Great Crimean War, 1854–1856
In the Austro-Prussian war of 1866, railroads were again key to mobilization on both sides, and the dryse needle gun and the French Chassepot Rifles were among the first "repeating rifles" used en masse by armies. (it was bolt action compared to the the lever action Spencer repeating rifle and Henry Repeating used in the US, but had the same fundamental impact of drastically increasing the rate of fire that could be put out by a given number of soldiers).
Typically when people talk about the bloody-ness of the civil war, they are often echoing General James Longstreet, who wrote in his diary that the new way of war necessitated defensive tactics, believing that men in fortifications with modern weapons could not be easily displaced by traditional massed infantry assaults of the Napoleonic era. It was this belief that led Longstreet to argue with Lee about Lee's planned assault on the Union Center during the third day of the battle of Gettysburg (what would become known as Pickett's charge).
A Equivalent european lesson might be the Battle of Gravelotte in 1870 in the Franco Prussian war. A Prussian army of 188,000 men intercepted a retreating french army of about 112,000. The french dug in along a ridge line and the prussians assaulted en masse supported by artillery bombardment, not all that differently from Confederate actions on the third day of the battle of gettysburg. In a single day of battle more than 12,000 prussian soldiers were killed Casualties and 8000 french soldiers were killed Casualties That's roughly half of what the battle of Gettysburg was over three days.
One thing that I think a lot of people discount when trying to argue that the Civil War had little to no impact on the mentality of European military thinking, is that the Civil War solidified many already drawn conclusions.
If one looks at this map, you can see that France is roughly the size of the state of Texas. What does this have to do with anything you might ask?
The absolute importance of railroad and telegraph communication. For example, the Vicksburg Campaign of 1863, took up an operational area the size of all of the West Coast of France below Brittany. That's roughly 32,000 square miles.
The logistics of this theater were largely based around the main rail lines running North to South and East to West in the state, and were the largest means of rapidly moving reinforcements up to fifty miles in a day. In this map, you can see that the area of the Crimea Campaign barely comprises the center of the State of Mississippi, but also almost the entire Northern Virginia theater of the Civil War.
During the Civil War, Lincoln was daily apprised of events as far away as the Indian Territory, Missouri, and Mississippi, on an hourly scale, giving him overview of military operations hundreds of miles away in the space of time, where if he so chose, he could give real time orders to influence a battle in progress.
While the Europeans relied upon telegraphs and railroads in their wars of the 1840's and 50s, the Civil War demonstrated conclusively that they had become indispensable tools of war as the scale of distance and size of operational theaters dwarfed entire countries of Europe. Entire armies could be moved, resupplied, and remain in communication on a scale unheard of in history thanks to the extensive rail and telegraph system.
Yes, significantly. The introduction of a bored cannon for accuracy and affect (30-pdr Parrott Rifled Cannon) on Fort Pulaski during the Civil War proved that there was no safe fortress of fortification in Europe. http://www.nps.gov/fopu/index.htm http://www.nps.gov/fopu/learn/historyculture/rifled-cannon.htm
Can I piggyback on this question and ask whether European military events in the earlier half of the 19th century, like the revolutions of 1848, have any influence on the lead up to the American Civil War?
One thing I heard in class, is that it had an impact on railroad construction... It is said that this is the first war with quick redeployment of troops (thanks to the trains) European countries soon realized that different sizes of rails would prevent quick foreign invasions.
I went back and revisited the applicable chapter of McElwee's The Art of War: Waterloo to Mons (entitled nicely "War Conducted by Amateurs: The American Civil War." McElwee taught at Sandhurst in the '60s.) McElwee makes three points not here-to-fore made and/or rebutted. The first:
Of the technical observers it was the Engineers who came back with the most useful information. This was, after all, a sphere in which the the amateur was the more professional and could comfortably outmatch the military specialist; and it was a war in which the smashing up of railways, bridges, tunnels, and their repair bulked particularly large in tactics. They brought back, therefore, especially from watching the Construction Corps of the Northern army, some remarkable accounts of bridges of record length rebuilt in record time, and much valuable information on the techniques of railway demolition and repair, though none of the European armies save the Russian made much use of it in their subsequent campaigns. They also learnt a lot about the hasty construction of gun emplacements and field fortifications for both infantry and calvary, all of which might have been of great value in the immediate future if the General Staffs had cared to make use of it.
Second, McElwee is of unstinting high regard for Sherman:
It was not until 1928 that Sherman's strategy of the 'Indirect Approach' was thoroughly analysed and reduced to its first principles by Captain B. H. Liddell Hart, and they were not put into practice with ruthless clarity and success until the battle of Alamein.
And third:
Forrest and Morgan were the only two generals who right from the start adopted the tactic of using their horses for movement only and fighting on foot. ... Simultaneously with this development of the use of exclusively mounted forces for long-distance raids, the American generals evolved an entirely new technique for using large masses of cavalry as a component of a lightly equipped force of all arms to operate independently of a main army against an enemy's flank or rear.
This is one thing that really fascinates me is how warfare evolves especially in the early modern times. Like how warfare different from the 1750s-1770's and the Napoleonic wars(1800-1815). And then how was it different from 1815-1850's etc. And then even going back further into the 1600's and the pikes and matchlock warfare and how did that evolve into pure muskets/arty/cav.
I know European military observers were present at many major battles, which is why it's worth pointing out that essentially every war is a military strategy and technological demonstration.
If you read through various texts of various wars you'll find that someone is always watching, recording notes so that when they go to war, they'll be better.
Ironclad ships were recognized as the new ship of the line and necessary for a sufficient fleet
Add on: I got the impression from light reading and the Ken Burns film that the technology outpaced tactical theory. That is, the guns got a lot more deadly, but the tactics of both sides were of the Napoleonic tradition of marching huge armies into each other, trying to break lines.
My question is, putting any aside European military snobbery, should there have been more of a lesson? That is, should the civil war been an example of lines of why warfare needed to modernize beyond the style of infantry standing in relatively open areas and firing at each other?
A While back I read a book called When the Guns Roared by Philip Van Doren Stern. It's a bit dated, mid sixties I believe, but it does a great job on the subject. The American Civil War did have a big impact on Europe's militaries. Not just the ironclads, but the gatling gun in particular. The new artillery invented by the Americans pretty much changed the European view of tactics.
The advancements changed the way European countries chose to develop their militaries further, and set them on the course for their own advantages or disadvantages in later wars.