During the bastan death march

World War II - Philippines (A forced walk of more that 50 miles)

Explanation:

In WWII (1939 - 45), around 70000 American and Filipino Prisoners of war were forcefully transferred from Mariveles in Bataan Peninsula and other parts of Philippines to Camp O'Donnel and other prison camps. These prisoners were made to walk for more than 50 miles before they were loaded on a train. The deaths though exact number is not known are said to be more than 20000 both American and Filipinos prisoners.

The unfree labors were able to improve the economy of the American society. These unfree laborers were the one manning farms and help in mass production. During this time when the US was concentrating on the agricultural sector, many landowners hired unfree labors. Many landowners would hire them because they have cheap labor and they can work longer than expected working hours.