What was the result of the Battle of Long Island?

Washington retreated, quickly!

This was Washington's first foray on the battlefield against the British and he was both unprepared and woefully overmatched. Washington's position was so precarious that had it not been for a fog that set it allowing his escape, Washington and the entire continental army would have been defeated right there.

As it was, Washington retreated up Manhattan to Ft. Washington where he crossed the Hudson River with as many troops as he could get across.

Those who were stranded on the wrong side were captured by the British and quickly lined up and killed in full view of Washington and his troops.