Through the 1880s Carnegie Steel installed open hearth furnaces and continuous production at its Homestead, Pennsylvania plant to fill U.S. Navy armor plate contracts, eroding the bargaining power of skilled workers. After an 1889 strike win, the Amalgamated Association of Iron and Steel Workers ran the floor under a 58-page rulebook. With the contract expiring June 30, 1892, Andrew Carnegie, who publicly defended unions, left for an estate in Scotland and had Henry Clay Frick stockpile steel. Frick demanded a 22% wage cut, locked the workers out on June 28 and 29, and ringed the plant with barbed wire, sniper towers and water cannons, a compound workers called Fort Frick.

The union took control of the town, and late on July 5 Frick sent 300 Pinkerton agents up the Monongahela on two barges. At 2:30 a.m. on July 6 the plant whistle roused thousands to the riverbank. After the tug fled, strikers attacked the stranded barges for 12 hours with a 20-pounder brass cannon, dynamite, a burning raft, a flaming railroad car and oil poured on the river. The Pinkertons surrendered at 5 p.m. and were beaten as they walked to the opera house. On July 12 Governor Robert E. Pattison sent 4,000 militia, and on July 23 anarchist Alexander Berkman shot and stabbed Frick, who survived.

• Many Pinkertons were men hired from lodging houses for about $2.50 a day who did not know their mission.
• About seven to ten Pinkertons and seven to nine strikers died, with dozens more badly injured.
• Berkman, who had no ties to the union, was sentenced to 22 years, and the union condemned the attack.
• On November 20, 1892, the workers voted 101 to 91 to return on Carnegie’s terms.
• The defeat kept unions out of American steel until the late 1930s; the union’s Bost Building is now a landmark.