At no point did textbook or teacher make any assertion about the morality/immorality/justice/injustice of any particular side in any of them.
I didn't learn about the firebombing of Dresden from History class, I learned about it from Vonnegut. I may have learned about the bombing of civilians in Hiroshima and Nagasaki in my history class, but their moral dimension was summed up by "It made Japan surrender," which is ahistorical bullshit. I didn't learn about the Tuskegee syphilis experiment at all, nor much at all about the racial prejudice that dominated American culture for a hundred years after the civil war (and continues to have lasting effects today).
American History as taught in US high schools is hagiographic, make no mistake about it.
Surely you learned about the Trail of Tears, Slavery, and the Vietnam War?
Here in New England I can tell you that I came out of 10th grade admiring Ho Chi Minh and despising Andrew Jackson.
You can avoid moral stickers but still be biased if you selectively choose which events to dive into.