"Defense is the stronger from of combat" - - Clausewitz.
"Yoo hoo, General Grant, remember me? I was wounded at Cold Harbor."
From Trevor Dupuy "Understanding War": Historical Eras and Innovations in Weapons.
"An important and dramatic change in the waging of war occurred in the decade between 1850 and 1860. This was the result of the introduction of an apparently minor improvement in small arms; the conoidal bullet for the infantryman's rifled musket. NO OTHER TECHNOLOGICAL CHANGE IN WEAPONRY, BEFORE OR SINCE, HAS HAD A COMPARABLE, DIRECTLY DISCERNIBLE, IMMEDIATE EFFECT ON THE BATTLEFIELD. [MY EMPHASIS]"
That infantryman of the period wielding the muzzle-loading rifle firing a conoidal round able to in a pronounced manner:
* Fire further.
* Fire faster.
* Fire with greater accuracy.
* Fire with greater lethality?
Once more from Dupuy:
"During the French Revolutionary and Napoleonic Wars, and through the last years of the Old era . . . artillery was responsible for 50 % or more of the battle casualties . . . After 1860 (American Civil war, the Austro-Prussian War, and the Franco-Prussian War), artillery was responsible for barely 10 % of the casualties. Small arms (rifled Muskets) were responsible for nearly 90 % of the casualties inflicted."
More so than the mere new technology and the application thereof it was the continued used of tactics and formations during an assault [offensive action] the methods as would have been found five decades earlier during the Napoleonic conflicts.
Clumped and tightly packed formations of infantry advancing across open ground the adversary defending while occupying trenches. [called breastworks during that period]
From those various battles of the American Civil War that muzzle-loaded rifle firing a conoidal round the casualties horrific as exemplified by:
* Cold Harbor.
Gettysburg 5,000 casualties in thirty minutes, Cold Harbor 10,000 casualties in ten minutes!! Union troops at Fredericksburg certain units when advancing told to hold their fire and use bayonets only, NOT able to reply to the entrenched and prepared Confederates.
War in that immediate period following the American Civil War [Franco-Prussian war, 1870 and Russo-Turkish War, 1877] the various combatants employing even more devastating firepower infantry equipped with breech-loaded single shot rifles THOSE IN COMMAND DURING AN ASSAULT PERSISTENTLY AND AS AUTOMATONS CONTINUING TO USE THOSE CLOSED AND CLUMPED FORMATIONS OF INFANTRY ADVANCING ACROSS OPEN GROUND!! NAPOLEONIC STYLE OFFENSIVE ACTION WITH DISASTROUS CONSEQUENCES!
Those single-shot breech-loaded rifles of the period to include the Dreyse "needle gun", the French Chassepot and the Peabody-Martini.
"The Chassepot, officially known as Fusil modèle 1866, was a bolt action military breechloading rifle, famous as the arm of the French forces in the Franco-Prussian War of 1870 and 1871 . . . in 1866, the Chassepot marked the commencement of the era of modern bolt action, breech-loading, military rifles."
"The Dreyse needle-gun . . . was a military breechloading rifle, famous as the main infantry weapon of the Prussians, who accepted it for service in 1841 . . . with the name chosen to hide the revolutionary nature of the new weapon"
From the Franco-Prussian War of 1870:
* Mars-la-Tour. 5,000 DEAD in fifteen minutes!
* St. Privet. 8,000 casualties in twenty minutes!
AND from the Russo-Turkish War of 1877:
"I am sending forth battalions and only squads return"
"On 11 September  the Russians and Romanians made a large-scale assault on Plevna. The Ottoman forces were dug in and equipped with Krupp-manufactured steel breech-loading artillery and American-manufactured Winchester repeaters and Peabody-Martini rifles. For three hours they poured murderous fire into the waves of advancing Russians . . . From the beginning of September, Russian losses had amounted to roughly 20,000, while the Ottomans lost 5,000."
That Peabody-Martini used at long range, the Turk commencing fire using plunging rounds at a distance of one mile [1 1/2 kilometers] and using that American Winchester 73 lever action rifle when the Russian had advanced to within 200 yards [200 meters give or take a few] of the Turkish positions. Absolute murder!!
I hate to say this but the American experience in Iraq and Afghan by comparison has been a gemuthlichkeit? A happy time except consider this amazing stuff:
"Early in 2010 and 2011, United States Marines recovered at least three from various Taliban weapons caches in Marjah. In April 2011, another Martini-Henry rifle was found near Orgun in Paktika Province by United States Army's 101st Airborne Division (Air Assault)."
That Afghan with nostalgia preferring the old ways and weapons. And where exactly do they find the ammo for those old Peabody-Martini?