We laud as heroes men and women who fight for a cause, or speak moving words, or stand up for timeless ideals—and rightly so. Yet some of the greatest heroes of World War II were the men and women on the home front, who applied their cleverness, tenacity, and famous American entrepreneurial innovation to equip the soldiers abroad with the tools needed for victory. Saginaw Steering Gear, a division of General Motors, was one such company: Its ingenious application of automotive assembly-line principles to the manufacture of the storied Browning M1919 machine gun gave the American GI and his allies the firepower to prevail over tyranny….