Why was the end of the civil war the bloodiest?

The Civil War was America's bloodiest conflict. ... Nearly as many men died in captivity during the Civil War as were killed in the whole of the Vietnam War. Hundreds of thousands died of disease. Roughly 2% of the population, an estimated 620,000 men, lost their lives in the line of duty. :)

Explanation:

the space race was a battle to make advanced technology to get to the moon and to get a better understanding of space.