The arrival of a British naval squadron at Quebec City on 6 May 1776 constitutes one of the decisive operational episodes of the American Revolutionary War's northern theatre. Following the failed American assault of 31 December 1775 and the protracted, disease-ridden investment that followed under Brigadier General Benedict Arnold and, subsequently, Major General John Thomas, the besieged garrison under Lieutenant General Sir Guy Carleton had passed the winter in a state of siege punctuated by sporadic exchanges of artillery fire. The thawing of the St. Lawrence in late April permitted the resumption of maritime traffic to Quebec, and with it the possibility of relief from the Atlantic.