The immediate purpose was to give protection to the defenseless frontier settlements. This was to be accomplished by destroying the Indian villages and sources of food supply, and by driving the Indians westward and northward.
A second objective was to cut off the food supply of corn and dried vegetables and fruits, which had been going from the Indians to the Loyalists and British for waging the war.
A third part of the plan was to capture the strong forts at Oswego and Niagara which were storehouses of the enemy and bases for military operations.
The most important objective has been entirely overlooked by most historians… Washington and other leaders saw that independence with a mere fringe of land along the seacoast would scarcely be worth the cost of the struggle if the rest of the continent to the westward and northward remained in the hands of the motherland. Washington knew by actual experience the potential wealth of the fertile regions of the interior of the continent. He realized that when the time came to discuss terms of peace that rich area could be secured for the young nation only if it was in possession of the Americans.
Hence in The Sullivan Clinton Expedition an inland empire was the stake for which Washington was playing and not merely the punishment of dusky foes on our border.
Alexander C. Flick Historian of the State of New York 1929