text: ADVANCE FOR USE SATURDAY, FEB. 6, AND THEREAFTER - FILE - This is an undated 1860's file photo of a military police detachment, known as provost guards, of the 107th U.S. Colored Infantry lined up at Fort Corcoran near Washington, D.C. It's been 150 years since black soldiers from U.S. Colored Infantry units began returning home from their service in the South, where more than 175,000 members fought - and in some cases, died - to free fellow African-Americans from slavery. (AP Photo/Library of Congress, File