The "reserve army of labor" is the group of workers found at the very bottom of the working class. They are typically very poor and unemployed, but the country does need a "reserve army of labor" to do the dirty work; jobs that require the lowest level of skill and also pay the lowest wage. The upper and middle classes would never want to perform a job that was lower than their standard occupation, but sometimes our nation has "extra jobs" due to war or a thriving economy. The people who do not have jobs are offered these "extra jobs" and I assume they do not pass them up. unfortunately, when the need for these "extra jobs" ends, the need to employ these people also ends. The nation actually needs these people, but only when it is convenient for the nation. So when upper and middle class people get upset about welfare and other public assistance programs they need to remember how the "reserve army of labor" actually comes to the nations' rescue when in need.