Final answer:
The research on Union letters tends to underrepresent minority groups such as African American Union soldiers and other racial and ethnic minorities. Historians have sought to recognize these groups by examining various documents to shed light on their experiences. Societal strategies and discriminatory practices against these groups are also part of the historical narrative.
Step-by-step explanation:
Research depicting the Union letters from the Civil War period often focuses on larger, more recognized groups, leaving certain populations underrepresented. In particular, the experiences of black Union soldiers, like the one from the 55th Massachusetts, highlight the unrepresented voices in historical accounts. Historians have since attempted to uncover the history "from the bottom up" by examining church records, newspapers, and court hearings, which helped to illuminate the lives and experiences of previously ignored groups such as the poor, illiterate, as well as racial, and ethnic minorities.
Within these historical studies, certain strategies were employed by the dominant society to maintain control and impose racial hierarchies on various groups, including African Americans, Native Americans, and immigrant populations. Suffragists' strategies for obtaining the right to vote also had racial and class implications, as illustrated by the contrasting perspectives and occasional prejudice from otherwise progressive figures like Thaddeus Stephens and Elizabeth Cady Stanton.
Finally, the letter from the black Union soldier and societal realities such as the forced segregation of African American troops and the disproportionate violence against African Americans during Reconstruction, reveal a pattern of systemic discrimination and underrepresentation that affected multiple marginalized groups throughout American history.