I do believe more than 10,000 people died.
Union death toll was 360,222; Confederate death toll: 258,000. A total of 613,222 deaths from The Civil War.
Massive.
Sri-Lanka, death toll 3000000 to 5000000.
If the question is asking about the Civil War battle with the highest death toll, I believe it was the Battle of Antietam.
4210 confirmed deaths.
2,100 american death for the first year in ww1,
Civil War (1861–1865) Total servicemembers (Union) 2,213,363 Battle deaths (Union) 140,414 Other deaths in service (nontheater) (Union) 224,097 Nonmortal woundings (Union) 281,881 Total servicemembers (Conf.) 1,050,000 Battle deaths (Conf.) 74,524 Other deaths in service (nontheater) (Conf.) 59,297 Nonmortal woundings (Conf.) unknown
The death tool of English, Americans, and German totaled about 51,000. I am not sure about French.
More people died post operation from gangrene than from the initial wounds the received on the battlefield. This was because of the lack of development of medicine at the time.
The American Experience - 1988 Death and the Civil War 24-8 was released on: USA: 12 September 2012
The American Experience - 1988 Death and the Civil War 24-8 is rated/received certificates of: USA:TV-14
Lack of medical facilities. Confedeate obstinacy - just not knowing when they were beaten.