First Things First:

Click on each magnifying glass to learn more about the source.

“…who are part and parcel of the white soldier in this great struggle against rebellion” Here the petitioners suggest that African Americans viewed themselves as stakeholders in the Civil War and recognized the part they played in aiding the Union.
“We are not contrabands, but soldiers of the U.S. Army…” This quote highlights the different connotations that existed with the different labels African Americans were given. The title of soldier implied citizenship and honor, unlike ‘slave,’ ‘contraband,’ or even ‘freedman.'
“we are now sharing equally the dangers and hardships in this mighty contest, and should shair [sic] the same privileges and rights …” This call for equality underscored how African Americans were treated as less than, despite facing the same risks and sacrifices. It was this argument that would be the backbone of the Civil Rights Movement a century later.
Think about it:

What can this gravestone tell us about the memorialization of Confederate war dead in 1879, when Confederate Mound was created?