(down) in the trenches

The place, situation, or environment in which the most difficult or demanding work takes place. Sure, you need strong leadership for a project like this to take shape, but it's the people down in the trenches putting everything into practice who make it all work. I spent nearly five years working in the trenches dealing directly with customers and suppliers, so when an opportunity in upper management came up, I was more than happy to take it. How can you begrudge us a raise when we're the ones down in the trenches, making all of your products in the factory?