England's three pronged attack to defeat of the patriots was to end in which city

Upper Canada from Detroit.

Explanation:

The British wanted to isolate New England from the other colonies. If the British controlled New York, this could be done. General Howe planned a three-pronged attack in October 1777. A three pronged attack is an attack in three separate places against an enemy.

General Howe planned a three-pronged attack in October 1777. A three pronged attack is an attack in three separate places against an enemy. ... General Howe would reinforce from the South. The British intended to destroy the American army.

Initial plans called for a three-pronged offensive: from Lake Champlain to Montreal; across the Niagara frontier; and into Upper Canada from Detroit. The Treaty of Ghent was signed by British and American delegates on December 24, 1814, effectively ending the War of 1812.