Complex sentence: On October 11, General William Howe moved the British army to Westchester County, New York and Washington moved the American army into Westchester too in order to escape entrapment if the British cut off the line of retreat from Northern Manhattan Island.
Split into simpler sentences: On October 11, General William Howe moved the British army to Westchester County, New York. In response, Washington also moved the American army into Westchester in order to escape entrapment if the British cut off the line of retreat from Northern Manhattan Island.