Washington established his headquarters at the Elijah Miller House in North White Plains on October 23, and chose a defensive position that he fortified with two lines of entrenchments. The trenches were situated on raised terrain, protected on the right by the swampy ground near the Bronx River, with steeper hills further back as a place of retreat. The American defenses were long. Beyond that, on the right, was Chatterton's Hill, which commanded the plain over which the British would have to advance. The hill was initially occupied by militia companies numbering several hundred, probably including John Brooks' Massachusetts militia company.