The first significant military action of the American Revolution happened on December 14 and 15, 1774, at Fort William and Mary in New Castle, New Hampshire, an event known as the "Portsmouth Alarm." Tensions between the American colonies and British authorities had been escalating, especially after the Intolerable Acts were passed in response to the Boston Tea Party. Reports had reached New Hampshire that British troops might be moving from Boston to Fort William and Mary to secure its munitions, which included a substantial supply of gunpowder. Paul Revere warned Portsmouth about these plans on December 13, 1774, prompting local Patriot leaders to mobilize around 400 militiamen from areas like Exeter, Durham, and Dover. On December 14, these militiamen marched to New Castle and arrived at the fort, which was manned by only a small group of British soldiers under Captain John Cochran. Around 3:30 PM, the militiamen demanded the surrender of the fort's gunpowder, and after some resistance, they overran the fort, capturing about 100 barrels of gunpowder which they took away. The following day, December 15, another group of militiamen returned to the fort, taking more supplies including muskets, cannons, and additional gunpowder. The British soldiers, overwhelmed, surrendered without significant resistance, although there was some shooting, resulting in one militiaman being slightly wounded but no fatalities. The captured supplies were distributed among local militias, significantly aiding their later resistance against British forces. This event was one of the first overt acts of rebellion, signaling the colonies' readiness to transition from political protest to armed resistance, heightening tensions that would lead to the Battles of Lexington and Concord in April 1775.