When the minutemen faced the british redcoats at the start of the battle of lexington, why did their captain yell, "don't fire unless fired upon"?

At this time the Minutemen faced the British Redcoats and the Captain had this expression because he was willing to persuade the enemies not to start a war and was just trying to keep and keep his men standing and defend themselves against the enemies only if it was necessary.

This sentence is true.