Answer:
Correct answer is the battle of Concord.
Explanation:
At the title of the poem itself says the poem is dedicated to one of the first battles of the Revolutionary War - Battle of Concord. Force of British officer Thomas Gage on April 19, 1775 had a conflict with American militia, that opened the door for more battles that happened in the colony of Massachusetts. Emerson wanted to present the heroic effort of the Patriots against the red coats.