Blocher's Run is a Pennsylvania stream which flows from Oak Ridge (triple watershed point at 39.858792°N 77.24483°W / 39.858792; -77.24483) on the Gettysburg Battlefield eastward to the Rock Creek (39.847665°N 77.225797°W / 39.847665; -77.225797) through and near areas of the Battle of Gettysburg, First Day.
During the Battle of Gettysburg Confederate soldiers took cover behind the trees that lined the stream.
References
Blocher's Run Wikipedia(Text) CC BY-SA