An infamous explosion of violence a century ago in Colorado, which became known as the Ludlow Massacre, was rock bottom in what has been called the deadliest labor dispute in the nation’s history. But few people recall that just a few months later, on July 4, 1914, the strike reverberated emphatically in Manhattan.

That April, the state militia machine-gunned and burned a tent colony of striking miners, killing, among others, a dozen women and children. The United States Commission on Industrial Relations, which investigated the labor unrest, reserved some of its strongest criticism for the Rockefeller family, which controlled one of the companies involved in the strike.

The commission denounced the family’s “perversion of and contempt for government, the disregard of public welfare and the defiance of public opinion” — a finding that helped inspire the Rockefellers toward an enduring philanthropic agenda.

At 9:16 a.m. on July 4, 1914, a premature dynamite explosion in an anarchist bomb factory blew the roof off a tenement at 1626 Lexington Avenue, near 103rd Street, wrecking three floors, killing four people, injuring a score of others and spewing debris for blocks.