Who that day would be lying dead,Pierced by a British musket-ball (lines 109-110)
Another violent moment we don't have to look at straight on: we don't actually have to see this poor guy get plugged, but we know it's going to happen. Longfellow likes to play with time when it comes to showing the violence of the war. We know this random dead guy was killed long ago. In the poem, it hasn't happened yet, but the speaker knows it will. At the same time, we get the feeling that it's happening right now. In a cool way, Longfellow's poem lets us live in the past, present, and future at the same time.
How the British Regulars fired and fled,— How the farmers gave them ball for ball (lines 113-114)
Here's the positive side of the war story. No scary, sad violence or young men getting killed, just a bunch of tough colonists who beat back a much stronger and better prepared army. This is the standard story of the Revolutionary War that we can all feel good about. The British are faceless and cowardly, the Americans a bunch of raggedy farmers who throw off the tormentors. There's some truth in that version, but Longfellow makes it hard to forget the reality, too. He's already reminded to us that war is always "bloody work" (line 100).