Freedom
"Native Guard" directly treats the theme of freedom throughout its various sections. The individual sonnets follow the journey of a recently freed slave as he joins the Union Army. He quickly becomes disillusioned, however, as he sees the terrible carnage and desperation of war alongside the marked racism of his Union superiors. He frequently makes comparisons between his former and current lives, finding an unsettling lack of change. He suggests that the nature of his freedom is largely nominal, save for his ability to record the events that surround him. The poem chooses this particular historical moment to highlight the way in which freedom is not simply a binary state, but something informed by the treatment of an individual. As he witnesses his fellow Black soldiers labor intensely, starve, lose limbs, and perish unacknowledged, he wonders how "free" the Union has really made them.
War
The poem deals centrally with the theme of war and its aftereffects. By setting the poem in a prison and not a battlefield, Trethewey is better able to explore what is left behind after a conflict: prisoners, corpses, rations, and casualty notifications. The speaker describes the bad conditions which he and his other soldiers endure on a daily basis, offering descriptions of decaying bodies and starving soldiers. These moments underscore the horror of war, standing in contrast to the seeming nobility of the cause that the soldiers are fighting for. This contrast comes to the foreground in the moment when a general casually dismisses the deaths of a group of Black soldiers, leaving their bodies to rot on the battlefield. In examining these leftovers of conflict, the speaker draws attention to the inevitable costs of war, with a particular focus on the way that the Black soldiers' sacrifices and contributions are dismissed and forgotten.
Race
One of the poem's most overt themes is race. The speaker's experience with racism in the military reveals the way in which this kind of prejudice was not limited to slaveowners or even to the South. The speaker's superiors repeatedly treat the Black soldiers in degrading ways, dismissing their work, insulting them, and abandoning their bodies on the battlefield. The speaker uses these moments to dispel the perception of the Union Army as a safe haven for recently freed slaves. He also states that the costly sacrifices made by Black soldiers to the Northern cause remain almost totally unrecognized. The overall point he is making is that race plays a huge role in how these men are unfairly perceived, causing them to be treated unfairly even after they've been freed from slavery.
