Fun fact: Pinkerton is still around and is "the world's leading provider of corporate risk management solutions" [0]. Companies regularly hire Pinkerton muscle to handle "security threats" related to union organizing.

Interestingly, even Google retains Pinkerton to investigate internal leaks [1].

[0] https://www.pinkerton.com/

[1] https://newrepublic.com/article/147619/pinkertons-still-neve...