The opening shots in the American War of Independence. General Thomas Gage, appointed military governor of Massachusetts in 1774, moved to seize arms being collected by the rebels at Lexington and Concord. The British lost 273 soldiers, the American rebels lost 95. These skirmishes led to Gage’s army of 6500 regular soldiers in Boston being besieged by some 16,000 Massachusetts irregulars until the British were forced to withdraw by sea on 17 March 1776.
Editors. "Battles of Lexington and Concord lead to the siege of Boston". The Literary Encyclopedia. First published 01 February 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=4199, accessed 10 December 2013.]