Publishers produced many envelopes depicting soldiers. In some cases, the images were celebratory, like that of the Zouaves waving an American flag. The Union army consisted of more than seventy volunteer Zouave regiments, their soldiers recognizable by their stylish uniforms with short coats and billowy pants. Sentimental images of a soldier saying a poignant goodbye, uncertain of the future, were common. “The Girl I Left Behind Me,” an older song that became popular during the American Civil War, drew on this theme.