Final answer:
The lines from Ralph Waldo Emerson's "Concord Hymn" reference the Battle of Lexington and Concord, the first military engagements of the American Revolution, known for the "shot heard round the world."
Step-by-step explanation:
The excerpt from Ralph Waldo Emerson's "Concord Hymn" refers to the Battle of Lexington and Concord, which took place on April 19, 1775. This battle marked the beginning of the American Revolution. It is renowned for the "shot heard round the world," an event that symbolizes the start of open armed conflict between the colonies and Great Britain.
On that fateful day, the colonial militia met British forces at Concord's North Bridge. Although it remains unclear who fired the first shot, the event itself catalyzed the drive for American independence and led to the establishment of the Continental Army, commanded by George Washington. The conflict escalated into a full-scale war, culminating in the creation of the Declaration of Independence, authored primarily by Thomas Jefferson.