The Question:

I've been told the largest battle ever fought in the Western Hemisphere was fought early in the month of July. What was that battle?

The Answer:

It was the battle of Gettysburg, which was fought from July 1-3, 1863, during the American Civil War.

Estimates put the total number of troops engaged at around 160,000 (85,000 Federal and 75,000 Confederate).

—The Fact Monster