How did Carnegie's company break the union at the Homestead mills?

My answer: It broke the union after the company responded to the union's refusal to accept reduced wages by locking out union workers from the mill and announcing that it would hire nonunion labor. The company also hired 300 armed guards, and, in response, the locked-out workers gathered weapons. A battle broke out that left ten people dead, and due to this, the Pennsylvania state militia began to escort nonunion workers to the mills. These events, after four months, caused the strike to collapse, breaking the union.

Do you think it is far too long of an answer? Or have I included unnecessary information?

I think your answer is great. It answers the question very well.