The first was an admirable naval base, especially for sailing ships, for the reasons given by Rodney.

The second was then, as it is now, the greatest military position on the Atlantic coast of the United States; and although the two could not communicate by land, they did support each other as naval stations in a war essentially dependent upon maritime power.
Philadelphia served no purpose but to divide and distract British enterprise.

Absolutely dependent for maintenance upon the sea, the forces in it and in New York could not cooeperate; they could not even unite except by sea.

When Clinton relieved Howe as commander-in-chief, though less than a hundred miles away by land, he had to take a voyage of over two hundred miles, from New York to Philadelphia, half of it up a difficult river, to reach his station; and troops were transferred by the same tedious process.

In consequence of these conditions, the place had to be abandoned the instant that war with France made control of the sea even doubtful.