To avoid altering history, that must continue to be true.

Before we go, however, I want to brief you again on the matter of altering history.

So far, they haven't looked like the kind of team that could alter history.

The only stipulation being is not to alter recorded history.

Still, how much license to alter history makes sense?

"By involving the villagers, we increase our chance of altering history in a significant way."

A few hundred of these weapons brought back through time could alter history.

He knew he could not, of course, without altering history.

If someone's death would alter history, then that person can't be killed.

The moment that he sent it back, he would, in effect, have altered history.