B. They provided some protection against the Ku Klux Klan.
In 1870 and 1871 during reconstruction, and after the riots in Cleveland and Rutherford the 7th US Cavalry quelled the riots and arrested 40 people including the leader of the KKK in Rutherford Randolph A. Shotwell.
C. They ensured African American men were able to vote.
When reconstruction started almost 20,000 troops were deployed in the south, they protected the polling sites and helped keeping peace all trhought the south states.
