What countries were powerful in europe in 1849?

Which would make the best heading for this list of notes about the migration of african-americans during the reconstruction era?

What practical concern lay behind the promotion of longitudinally planned churches in 17th-century rome? a) allowing the circulation of pilgrimsb) interior lighting of the navec) support for the heavy domed) accommodating parishioners

Brainliesttt !me : ) -what is invisible warfare?