Andrew Carnegie, who attempted to portray a pro-labour image, left the country for a trip to Scotland before the strike occurred leaving the situation in the hands of Henry Clay Frick, who was well known to be staunchly anti-union.
The company attempted to cut the wages of the skilled steel workers, when the workers refused the pay cut, management locked the union out (therefore, the confrontation was actually a "lock-out" by management and not a "strike" by workers).
Frick brought in thousands of strikebreakers to work the steel mills and to safeguard them, brought in Pinkerton agents.
The arrival (on the 6th of July) of a force of hundreds of Pinkerton detectives from New York and Chicago resulted in a fight in which about 10 men were killed, and to restore order two brigades of the state militia were called out. However, the company successfully resumed operations without the union.
The skilled workers were replaced by unskilled, mostly immigrant labourers, and labour activism was infrequent in the Pittsburgh area steel mills for decades.