War and its Impact
It may seem strange to think of "Christmas Bells" as a war poem, but it does indeed evoke the terrible Civil War that beset America in 1861-1865. Holidays do not seem the same when the nation is at war, nor are they as happy when a member of the family has died or is gravely injured; this is the situation that Longfellow was facing when he wrote this poem. War has the ability to touch individual lives in that it harms or kills people we love, but also through its ability to make us doubt the future in a more general sense. Longfellow wonders if there is any reason to have hope when the fate of the country is in the balance; life as he knows it may vanish. War is thus a heavy, oppressive reality that is an emotional and metaphysical impediment to happiness.
Grief
Longfellow expresses grief over the country's entrenchment in the Civil War, but critics point to how he was also working through his grief related to his wife's death and his son's serious injury in the war. The threat that hope will fail when oppressive reality sinks in is grave in the case of both war and family tragedies. Longfellow does eventually decide that it is better to hope and believe that Right will triumph, but he makes it clear that worry and despair are fully human, and thus understandable.
Hope
The poem ends on a note of hope even though the middle stanzas show the poet wallowing in his despair and anxiety. Some people may consider hope foolhardy, but it is the only way to make life worth living. Hope is sustaining; hope is energizing. It gives those on the "Right" side the drive they need to continue persevering. Longfellow is demonstrating resiliency and renewal in this poem, and it is all the more encouraging given what we know about the background to the work.
