Labor unions typically protected workers when they went on strike by bargaining with employers to negotiate better working conditions, wages, and benefits for their members. This helped to ensure that the workers would not simply be replaced by other workers during the strike. The labor union would also provide financial assistance and support to the striking workers to help them sustain their livelihoods during the strike.
Additionally, labor unions often helped to protect workers from negative press and public opinion by promoting their cause and explaining the reasons for the strike. They also helped to organize picket lines and other forms of protest to draw attention to the workers' demands and put pressure on the employers to negotiate with the union.
Overall, labor unions played an important roll.