Powder Alarm The Powder Alarm was a major popular reaction to the removal of gunpowder from a magazine by British soldiers under orders from General Thomas Gage , royal governor of the Province of Massachusetts Bay , on September 1 , 1774 . In response to this action , 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 . Although it proved to be a false alarm , the Powder Alarm caused political and military leaders to proceed more carefully in the days ahead , and essentially provided a " dress rehearsal " for the Battles of Lexington and Concord seven and a half months later . Furthermore , actions on both sides to control weaponry , gunpowder , and other military supplies became more contentious , as the British sought to bring military stores more directly under their control , and the Patriot colonists sought to acquire them for their own use . Background . In 1772 , many of the thirteen British colonies , in response to unpopular British actions and the negative British reaction to the Gaspee Affair ( the destruction by colonists of a grounded ship involved in enforcing customs regulations ) , elected to form Committees of Correspondence . These allowed communities to formally communicate with each other , raise awareness of incidents occurring elsewhere , and to coordinate actions ; as such , they became instrumental in managing the colonial response to enforcement of the Tea Act , the Intolerable Acts , and other unpopular British colonial legislation . The colonists of Massachusetts had not yet taken concerted action to organize themselves militarily against actions of the British regulars , although statements were made about supporting Boston ( whose port had been closed earlier in 1774 under the Boston Port Act ) " at the risque of our lives and fortunes . " 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 British Parliament had passed in response to the Boston Tea Party . Seeking to prevent the outbreak of war and to keep the peace between the American Patriot ( Whig ) majority and the Loyalist ( Tory ) minority , he believed that the best way to accomplish this was by secretly removing military stores from storehouses and arsenals in New England . The secrecy of these missions was paramount , as Gage feared that leakage of any plans would result in the seizure or concealment of the stores by Patriot sympathizers before his men got there . There were several places throughout the colonies where the British army had stockpiled supplies . Some of these places were fortifications that were manned by small garrisons ; others were merely locked magazine s . Most of the powder in these was under the control of the provincial government , though some was the property of individual towns . One locked storehouse near Boston , in what was then part of Charlestown , now Powder House Square in Somerville , was controlled by William Brattle , the leader of the provincial militia and an appointee of the governor . Brattle , who had not obviously sided with either Loyalists or Patriots , notified Governor Gage in a letter dated August 27 that the provincial ( " King ' s " ) powder was the only supply remaining in that storehouse , as the towns had removed all of theirs . Gage decided that this powder had to be brought to Boston for safekeeping . Expedition . On August 31 , Gage sent Middlesex County sheriff David Phips to Brattle with orders to remove the provincial powder ; Brattle turned the key to the powderhouse over to Phips . Gage also gave orders to ready a force of troops for action the next day , something that did not go unnoticed by the local population . At some point that day , General Gage , whether by his intent , accident , or theft by a messenger , lost possession of William Brattle ' s letter ; the widely held story is that it was dropped . News of its content spread rapidly , and many considered it to be a warning to Gage to remove the provincial powder before Patriots could seize it . Early in the morning of September 1 , 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 in modern - day Somerville . From there they marched about a mile to the Powder House , a gunpowder magazine that held the largest supply of gunpowder in Massachusetts . Phips gave the King ' s Troops the keys to the building , and after sunrise they removed all of the gunpowder . Most of the regulars then returned to Boston the way they had come , but a small contingent marched to Cambridge , removed two field pieces , and took them to Boston by foot over the Great Bridge and up Boston Neck . The field pieces and powder were then taken from Boston to the British stronghold on Castle Island , then known as Castle William ( renamed Fort Independence in 1779 ) . Response to the raid . Rumors flew throughout the day across the countryside about the British troop movements . The regulars were marching ; provincial powder had been seized ; war was at hand ; people had been killed ; Boston was being bombarded by His Majesty ' s warships . The alarm spread as far as Connecticut . From all over the region , people took up arms and began streaming toward Boston . One traveler in Shrewsbury reported that in the space of 15 minutes , 50 men had gathered , equipped themselves , sent out messengers to surrounding towns , and left for Boston . On the 2nd , several thousand men bent on violence gathered in Cambridge , where they forced several notable Loyalists , including William Brattle , to flee to Boston and the protection of the military . Sheriff Phips was forced , in writing , to dissociate himself from any and all government actions . Eventually facts caught up with the rumors , and militia units ( some of which were still heading toward Boston ) returned home . Also on the 2nd , Boston newspapers published a letter from William Brattle in which he protested that he had not warned Gage to remove the powder ; Gage had requested from him an accounting of the storehouse ' s contents , and he had complied . The content of his letter to Gage would be published on the 5th . Brattle remained on Castle Island through the siege of Boston , leaving when the British evacuated the city in March 1776 . He died in Halifax , Nova Scotia in October 1776 at the age of 70 . British reaction . Gage , surprised by the size and scope of the colonial reaction , delayed and eventually cancelled a second planned expedition to the storehouse in Worcester . He concentrated his troops in Boston , and called for reinforcements from London , writing " if you think ten thousand men sufficient , send twenty ; if one million is thought enough , give two ; you save both blood and treasure in the end . " However , Gage ' s request was seen by some in London as absurd , as there were only 12 , 000 troops in Britain at the time , but he did eventually receive an additional 400 Marines in response to these requests . He later began planning and executing seizures again , and he further fortified the Boston peninsula . Colonial reaction . After the Powder Alarm , militia forces throughout New England were more cautious with their supplies and more intent on gaining information about Gage ' s plans and troop movements . Paul Revere played a significant role in distributing this information due to his geographical position in Boston , his social position as a middle - class craftsman in contact with all social classes , and his political position as a well - known Patriot propagandist and organizer . The colonists organize . On September 21 , 1774 , Patriot leaders met in Worcester and urged town meeting s to organize a third of the militias into special companies of minutemen in constant readiness to march . They also instituted the system of express riders and alarms that would prove to be critical at Lexington and Concord . In October , the former legislature of Massachusetts met in defiance of the Massachusetts Government Act and declared itself to be the First Provincial Congress . It created a modeled after a body with the same name during the English Civil War and it recommended that a quarter of the militia be designated as minutemen . Military stores were to be stockpiled away from the coast ( more than a convenient day ' s march ) , to make attempts to seize them more difficult . The largest stockpiles were located at Concord and Worcester . Portsmouth Alarm . Early in December , British military command voted to prohibit the export of arms and powder to North America , and to secure all remaining stores . On December 12 , intelligence received by Paul Revere indicated that a seizure of stores at Fort William and Mary in Portsmouth , New Hampshire was imminent . He rode from Boston to Portsmouth the next day to notify the local Patriots , who quickly raided the fort on the 14th and removed its supplies . Revere ' s intelligence had been incorrect ; although a British operation had been contemplated , it had not been ordered . The British did eventually send ships carrying troops to Portsmouth , but they arrived long after the event . The first arrived on the 17th , and was directed into shallows at high tide by a local Patriot pilot , much to the captain ' s anger . Stores of gunpowder — typically referred to by Loyalists as " the King ' s powder " and by Patriots as " the militia ' s powder " — were also carried off from forts in Newport , Rhode Island , Providence , Rhode Island , and New London , Connecticut and distributed to the militias in towns away from the coast . Cannon and other supplies were smuggled out of Boston and Charlestown . Salem confrontation . On February 27 , 1775 , HMS " Lively " brought a force of about 240 British regulars from the 64th Regiment under Colonel Alexander Leslie to confiscate weapons in Salem , Massachusetts . They were stopped by a small crowd that raised a drawbridge in their path and taunted them while others moved the cannon to safety and sent for help from nearby towns . Eventually , the drawbridge was lowered and the regulars were permitted to search the forge where the cannon had once been . They returned to their ship while being mocked by a growing force of irregulars marching along in lock - step next to them . There were minor scuffles , but no shots were fired .