It's not the number of people killed in the American Civil War, it's the percentage of the population killed.
Twenty five percent of all military aged men in the South were killed. Another twenty five percent of all military aged men in the South were maimed.
No country anywhere on the planet would see this percentage of casualties until certain areas, and only a relatively few, experienced such huge percentages during WWII. Heck, the world as a whole, only lost like what, two percent of it's population during WWII? And that was the most epic overall war humanity has ever seen.
You are forgetting the many small tribes which were defeated so badly that their tribal organization ended and the the survivors, if any, became assimilated into different peoples, thus ending their ethnic groups. For example, several nations that were ended by the Iroquois during the 17th century Beaver Wars, or the Yahi in California.
And among modern nations that had international diplomatic recognition several small nations involved in World War One and World War Two suffered civilian fatality rates equal or greater than the South's military fatality rate. And the winner, or rather loser, in this doleful competition is Paraguay which suffered the deaths of at lest 50 percent of its pre-war total population during 1864-1870.
I agree on the tremendous losses the South suffered ,it must have afflicted the South spirit grievously
as for some record on men losses ,
Paraguay war of the triple alliance was quite devastating with massive losses of men
like millions of men versus thousands , three orders of magnitude
Germans 200.000 ....Soviets 860.000
the fighting was prolonged and ferocious , in the air on the ground , in trenches , from artillery to hand to hand
After the UN Forces liberated the South Korean territories that were occupied by North Korea, the UN Forces advanced further north towards the Chinese border. 30,000 of the X Corps (UN Forces) deployed around the Chosin Reservoir became trapped by the Chinese military of 120,000 during the cold winter of the Korean War. More Chinese armies were deployed in the other areas of North Korea. With the help of the US Air Force, the X Corps fought their way out on a mountainous terrain. This was the US Army's longest retreat in history. After the X Corps reached a North Korean eastern coastal city called Hungnam, approximately 100,000 UN soldiers successfully evacuated to South Korea with approximately 100,000 civilians. 193 ships were assembled for this evacuation. In the western side of North Korea, more than 250,000 UN soldiers retreated to South Korea. The Communist side reached further south and retook Seoul. South of Seoul, the Communist armies outran their supply lines. With intense air and artillery firepower, the UN Forces stopped the Communist advance and liberated Seoul again. However, this was still in 1951. There would be another Communist offensive more massive than the previous one.
It's tough to use the term "epic" when describing history. It's usually reserved for the near-legendary stories of heroes & nations.
Personally I'll use the term to mean "going beyond the scope of the usual, so much so that it changes history".
What would fall into the "epic" catergory? Definitely WW II. Today we're living in the world created by this war. If you go back in history you come to the Congess of Vienna which ended 25 year of war and created a new world order that lasted up to WW I. You go back to ancient history and the epic consolidation of Rome as an empire via a series of civil wars is a turning point. It's legacy is still around today.
Today certain countries, and their world status, exist because of historical "epic" conflicts. Modern USA grew out of the Civil War. Modern China grew out of the Civil War.
So I think when you use the term "epic", it means it goes beyond in scope. It changes history and it seems to be known by the world community because it affects the world community.