The removal of colonial gunpowder by British soldiers, and the massive popular reaction known as Powder Alarm that ensued, are considered to be a turning point in the events leading up to war.

First built for use as a windmill by John Mallet in the early 1703 or 1704, the Old Powder House was sold to the colonial government of Massachusetts for use as a gunpowder magazine in 1747.

General Thomas Gage, who had become the military governor of Massachusetts in May 1774, was charged with enforcement of the highly unpopular Intolerable Acts, which the British Parliament had passed in response to the Boston Tea Party.

[3] Just after dawn on September 1, 1774, a force of roughly 260 British regulars from the 4th Regiment, under the command of Lieutenant Colonel George Maddison, were rowed in secrecy up the Mystic River from Boston to a landing point near Winter Hill.

[5] In response to the raid, amid rumors that blood had been shed, alarm spread through the countryside as far as Connecticut and beyond, and American Patriots sprang into action, fearing that war was at hand.

Thousands of militiamen began streaming toward Boston and Cambridge, and mob action forced Loyalists and some government officials to flee to the protection of the British Army.

[6] This did however, inflame already heated feelings on both sides and would spur actions by both British and American forces to move both powder and cannons to secure locations.

The Field House was constructed in 1935-36 using stones from the 1934-demolished Somerville Highlands railroad station, which had closed in 1927 when passenger service on the Fitchburg Cutoff ended.

Several businesses thrive on or around Powder House Square, including restaurants, several small medical and dental practices, and a funeral home.