Why was the freedmen's bureau established by congress during southern reconstruction?

 To help former slaves make the change to freedom

Details:

The Freedmen's Bureau was established by Congress in 1865, in the aftermath of the Civil War.  The aim of the Bureau was to provide assistance to former black slaves (as well as poor whites) in the South during the Reconstruction period.  The Freedmen’s Bureau provided food and housing, established schools, and made medical and legal assistance available.  There was an intention of settling former slaves on land confiscated or abandoned during the war, but that didn't materialize. Radical Republicans took over dominance in Congress and they determined that confiscated lands in the South should be returned to their original owners.

in this part of the declaration it refers to the point when american people didn't recognize the british domain and   breaks the political bands with britain, they forced a respectful separation.

mankind was created and entitled equally with rights   which were life, freedom and the seeking for happiness.