At the outbreak of the War of 1812, the United States had only one warship in Lake Ontario, so it had to repurpose civilian vessels for military use. Sackets Harbor, New York became a principal port and shipbuilding yard for the upper St. Lawrence River Valley and Lake Ontario. The U.S. built several forts to protect the harbor, including forts Tompkins, Pike, Volunteer, Kentucky, Virginia, and Chauncey. In the First Battle of Sackets Harbor, July 19, 1812, American cannons on shore chased away five British ships pursuing a merchant vessel, severely damaging the British flagship Royal George.
In late May 1813, the American fleet was preoccupied at Fort George, near the mouth of the Niagara River. The British took advantage of its absence and attempted to seize and destroy the shipyard and supplies at Sackets Harbor. Captain James Lucas Yeo took six ships (with a total of 700 crew and 98 cannon) and approximately 870 men, consisting of a grenadier company from the 100th Regiment, two companies of the 8th Regiment of Foot, four companies of the 104th Regiment, one company of the Glengarry Light Infantry, two companies of the Canadian Voltigeurs, and a detachment of Royal Artillery with two 6-pounder guns, and sailed south. Approximately 37-40 American Indian warriors accompanied them.
On May 28, the British intercepted 12 small boats carrying reinforcements from the 9th and 21st U.S. Regiments from Oswego to Sackets Harbor in Henderson Bay. They landed at a rocky outcropping called Stoney Point and fled into the wilderness, only to be overtaken by hostile American Indians. The 9th and 21st were virtually destroyed, losing 35 men. The remaining 115 surrendered. Only seven men escaped and made it back to Sackets Harbor.
By that time, Lieutenant Colonel Electus Backus of the 1st Regiment of Light Dragoons assembled 400 regulars, 250 Albany Volunteers, and 550 local militia, led by Brigadier General Jacob Brown, to oppose the British invasion.
Before dawn on May 29, the British force landed at Horse Island, several miles west of Sackets Harbor, and crossed the narrow straight to the mainland. They split into two wings. One advanced east parallel to the shore toward the navy yard and the other moved southeast through a wooded area, protecting the right flank. American militia opposed the landing, but fell back to pre-planned defensive lines as the British advanced.