Pete Geren became the 20th Secretary of the Army Friday.   As Secretary of the Army, he has statutory responsibility for all matters relating to the U.S. Army: manpower, personnel, reserve affairs, installations, environmental issues, weapons systems and equipment acquisition, communications and financial management.  He is responsible for the Department of the Army's annual budget and supplemental of $170 billion. He leads a work force of more than one million active-duty and reserve-component Soldiers, 230,000 Department of the Army civilian employees and 280,000 contracted service personnel. He has stewardship over 15 million acres of land.