In the wake of Lexington and Concord, some places didn’t wait to start assembling troops to fight off the British. Most of them were in that part of the Colonies, though.
Enter the Berkeley County Riflemen, from a section of Virginia that is now West Virginia. George Washington put out the word that soldiers were needed, and about a hundred men from Martinsburg stepped up, even going so far as to ensure that they dressed mostly alike, since there was no Continental Army just yet, and therefore there were no uniforms.
And while the sign doesn’t really say much about it, the Berkeley County Riflemen are said to be the genesis of the United States Army.