The labor violence that escalated from the late 1800s to the late 1930s was eventually defused by the grand liberal bargain, enshrined in the Wagner Act. Unions were strengthened and given the tools to protect their members from the assault of capital. As productivity grew, the income of the workers grew. It was a fair bargain: it led to a rational sharing of the rewards from the economy. Sean Wilentz tells us that the Wagner Act was the culmination of decades of work by liberals. Senator Wagner himself was motivated by the Triangle Shirt Waist fire.