Why were the buffalo soldiers given their name?

Another possible source could be from the Plains Indians who gave them that name because of the bison coats they wore in winter. The term Buffalo Soldiers became a generic term for all black soldiers.

freedom of speech is also protected by the 1 amendment.

explanation:

here is pretty much what the 1st amendment says:

congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances.