British blockade of continental Europe interfered with American trade, and some British naval vessels inflamed sentiments by impressing American seamen. These factors conspired with the interests of Western American politicians who wished to seize Canadian lands. War was declared on 16 June 1812 and battles occurred along the Canadian frontier through 1812 to 1814. York (now Toronto) was burned by the Americans in 1813, leading the British to retaliate by occupying Washington in August 1814 and burning the White House. Hostilities were concluded by the Treaty of Ghent (negotiated August-December 1814).