As cars zoom along Darnestown Road, drivers can glimpse the gently sloping pastures of historic Belward Farm, a wide swath of green in the middle of Montgomery County that has seen little change since the Civil War.¶ Even as tract mansions, shopping centers, roads and office parks have sprouted nearby, Belward has endured, looking today much as it did in the 19th century. Not long ago, Belward Farm was home to an 80-head herd of black Angus cattle, two miniature horses and a donkey, whose owner, Elizabeth Beall Banks, was a feisty opponent of development.