Final answer:
The National Labor Union (NLU) proposed an eight-hour day after the Civil War. They were successful in convincing Congress to adopt the eight-hour workday for federal employees.
Step-by-step explanation:
The National Labor Union (NLU) proposed an eight-hour day after the Civil War. The NLU was a national federation of trade unions founded in 1866 with the goal of promoting arbitration, a new political party based on the interest of laborers, and limiting the working day to eight hours. While they were successful in convincing Congress to adopt the eight-hour workday for federal employees, their reach did not progress much further.