[REVOLUTIONARY WAR]. Supplement to the Boston-Gazette, &c. of (No. 790). Boston: Edes & Gill, 21 May 1770. Broadsheet (381 x 248 mm), old folds, light soiling to upper portion. PRINTED SHORTLY AFTER THE BOSTON MASSACRE. On 5 March 1770, a group of nine British soldiers openly fired into a crowd of over 300 colonists forming around a British sentry, killing five and wounding six. The mob was fueled by a growing unrest in Boston over a series of acts passed by the British Parliament that raised revenue through duties on lead, glass, paper, paint, and tea. Afterwards, John Adams wrote that the “foundation of American independence was laid” and was heavily publicized as a “massacre” by Paul Revere and Samuel Adams, thus laying the groundwork for later rebellions, most famously the Boston Tea Party, effectively launching the American Revolution. Edes & Gill would print the rare Boston Massacre issue on 12 March 1770.