I apologize that I don't have a source in front of me, but in my reading of many books about the American Civil War, I've read of European military observers at the time, and historians later, commenting that the American militaries were poorly led and drilled: that officers at all levels generally didn't have a good grasp of tactics compared to their European counterparts, (especially compared to the armies of the Napoleonic Wars,) and that enlisted soldiers weren't nearly as well-drilled.
People saying these things will usually say that this is why American Civil War battles were almost always indecisive compared to say, Austerlitz or Waterloo. (Even when two big armies of each side fought, one could never totally rout the other. They just sort of fought and bled a lot until one retreated. There are exceptions, like Chancellorsville, but even then, that would be indecisive compared to a Napoleonic battle: the Army of the Potomac was not destroyed.)
This is also applied to explain why cavalry were relatively ineffective in Civil War combat; unable to decisively turn the tide of battles with charges.
Is there much truth to these sorts of claims? Or did the advances in technology between 1815 and 1861 make the nature of the battles different?
Thank you for any insights!
There are several differences between European and American (used here meaning USA and CSA) militaries of the time.
You are correct that European battles of the era usually were decisive - the losing army had to hole up in fortifications (where it was besieged until it surrendered) or were mercilessly pursued until it was no longer an effective fighting force. This happened at Inkermann 1854, at Solferino 1859, at Danevirke 1864, at Königgrätz 1866 and at Sedan 1870.
The European powers had military establishments that America lacked. There were a large cadre of career officers - professionals educated at military and cadet schools and officer schools and serving most of their life in the military. While West Point was (and is) a fine military school, many of its graduates left the army to pursue civilian careers - as lawyers, businessmen, planters or politicians since there was almost no military establishment to havea career in. Also, there were only 534 West Point graduates that would serve on either side in the American Civil War, to command armies that probably exceeded 1 500 000 men (combined CSA and USA forces). Likewise, there were no large cavalry establishment in America. American cavalry, as it were, fought either as mounted infantry or as skirmishers - harassing, raiding, recoinnasance or holding important terrain until reinforcements could arrive were what it was capable of. The American cavalry was too scarce in numbers and not well-trained enough to charge home and conduct battlefield pursuit. At Königgrätz 1866, the Prussian cavalry took more than 9 000 Austrian prisoners in less than an hour after the Austrian army started to retreat - and only stopped because the Austrian cavalry reserve counter-charged and threw them into disorder. Their battlefield pursuit was one of the chief reasons the Austrian army was incapable of another fight after the battle. I do not think tehcnology can account for the difference as the Europeans were capable of decisive victories like in the Napoleonic Wars, but the Americans were not.
European powers had learned from the Napoleonic Wars the need to have mobilisation plans, supply and organisational plans as well as an extensive staff to do planning for any battle, manouvre or campaign. The American amies lacked this completely. The most extensive experience any American armies had was Scott's Mexican expedition, a force that never exceeded 9 000 men at any given time. The few American officers lacked experience in both theoretical and practical staff work, logistics and supply organisation.
It is said that Helmuth von Moltke the elder called the American Civil War "two armed mobs chasing each other through the country, from which nothing can be learned". While he probably never said so (I have never found a reliable source saying it), the quote still captures a lot of the sentiment of how professional Europoean officers viewed much of the American Civil War.
Generally, the American armies had to start from absolutely nothing. Volunteer regiments were commanded by amateur officers which raised them. Tactics were based on Napoleonic Wars studies (an integral part of the curriculum at West Point) except that the armies lacked the cavalry arm of the Napoleonic Wars. Likewise, the various Corps organised by both sides often lacked an integral cavalry arm to screen their movement, keep enemy recoinassance at bay, do their own recoinassance and do battlefield pursuit.
Cavalry is harder to raise from nothing than infantry is. European cavalry had huge state-run horse farms to raise and train thousands of war horses. Not only did every cavalryman need a trained war horse capable of galopping straight towards large groups of humans and horses - he often needed more than one, as horses died and were wounded at a much higher rate than cavalrymen. America lacked this establishment as well. It is also much harder to drill troops to charge home into melee than it is to make them stand and fire. American troops demonstrated at several occassions that they were mostly incapable of charging home - instead they stayed at rifle distance and bravely took horrendous casualties exchanging fire with the defenders at the perfect killing distace - this happened at Fredericksburg, at Pickett's charge at Gettysburg and at Cold Harbor.
While the American armies got better and better as the war progressed, they were unable to properly condition their troops to kill. Marshal and Grossman (building on Marshals research) condlude that beyond about 100 meters, the American armies had a hit ratio of about 2% - with rifles of the era accurate to about 600 meters, they condlude that the American armies were unable to condition their troops to kill, and most stood bravely in the fire line, loaded and fired without aiming, even closing their eyes as they fired. Marshal and Grossman's research have been questioned and criticised lately, but it is still a relevant point to make.