Believing the British were burning their houses, the Minutemen, numbering about 400, advanced down a hill overlooking the bridge. The British guards quickly retreated across the bridge, attempting to destroy it in the process. During this process around 700 more British had arrived at the bridge, and the 400 Minutemen advanced, under the orders not to fire unless fired upon.
The Battle of Concord was started when a musket shot was fired from an unknown soldier. The Shot Heard 'Round the World was assumed to be a sign of aggression and the Battle of Concord began. Minutemen and the British soldiers exchanged volleys for a few minutes, resulting in about a dozen British casualties, and half of the British officers wounded. The British, forced to retreat back to Boston, were pursued by the Minutemen, and they found that the Americans had no problem using a guerrilla style of warfare.
The result of this battle was devastating for the British forces. The British casualty count was around 200-300, and their morale was severely damaged. Even though they were the largest, most advanced army in the world, they could not defeat the 400 colonists.
Upon hearing of the Battle of Concord, George Washington stated that the once peaceful plains of America were to be drenched in blood, and it is those blood-stained grounds that inspired the Town of Concord to built a monument to remember those on both sides who gave their lives defending what they believed in. The inscription on the monument reads: Here, on the 19th of April, 1775, was made the first forcible resistance to British aggression. On the opposite bank stood the American Militia. Here stood the invading Army and on this spot the First of the Enemy fell in the War of that Revolution which gave Independence to these United States. In gratitude to God and in the love of Freedom, this monument was erected AD. 1836.
Ralph Waldo Emerson also contributed to the memory of the battle by writing the famous Concord Hymn on July 4, 1837, at the dedication of the monument.