Facts: UK:Twenty-four men believed to have been held against their will and forced to work have been freed from a caravan site in Bedfordshire. US: Slavery was a form of slave labor which as a legal institution from the early colonial period. After the american revolution (1775-1783), the northern states all abolished slavery, and Congress prohibited slavery in the Northwest Territory. For more: http://en.wikipedia.org/wiki/Slavery_in_the_United_States