The road and railway bridge at Thanh Hoa south of Hanoi spanned the Ma River and was a vital link in the movement of communist troops and supplies. For the better part of a decade, U.S. Navy, Marine and Air Force aviators braved the flak-filled skies over North Vietnam on missions to destroy the 56-foot-wide bridge, christened the “Dragon’s Jaw” by locals, and sever that link.