The USN began construction of Byrd Station at 80°S, 120°W with traverses out of Little America V in 1956–57 during Deep Freeze II. These efforts were in advance of the International Geophysical Year (IGY; from July 1957 to end of 1958) that saw several exploratory overland traverses with tractor trains (Sno-cats and modified bulldozers). Starting in January 1957 (pre-IGY) Charles R. Bentley led a traverse from Little America V to the new Byrd station along the route blazed by United States Army engineers a few months before (the Army-Navy Drive[12]).