He embarked with a force of regulars, eight hundred men, on Sir James Yeo's ships at Kingston and sailed across Lake Ontario.
Sackett's Harbor was defended by only four hundred regulars of several regiments and about two hundred and fifty militia from Albany.

Couriers rode through the countryside as soon as the British ships were sighted, and several hundred volunteers came straggling in from farm and shop and mill.

In them was something of the old spirit of Lexington and Bunker Hill, and to lead them there was a real man and a soldier with his two feet under him, Jacob Brown, a brigadier general of the state militia, who consented to act in the emergency.

He knew what to do and how to communicate to his men his own unshaken courage.

On the beach of the beautiful little harbor he posted five hundred of his militia and volunteers to hamper the British landing.