What was the main cause of the strike at Carnegie's Homestead Mill? Andrew Carnegie had employed Civil War veterans in place of steelworkers. Anarchists intended to blow up the Homestead Steel Works near Pittsburgh. Andrew Carnegie wanted to break up the power of the steelworkers' union. Steelworkers left their jobs to enlist as soldiers since war with Spain was likely.

Andrew Carnegie wanted to break up the power of the steelworkers' union.

Explanation:

Following the success of the 1889 strike in which the steelworkers had won a favorable three-year contract, the outcome did not go down well with Andrew Carnegie who was hell-bent to reduce the influence of the workers' union.

To do this, he made changes to working conditions through his plant manager by demanding increased production and failure to meet up led to the sack of the majority of the workers.

Eventually, all the workers went on another strike in 1892