The song paints a narrative of a patriot, dedicated enough to give his life for his country in the earnest belief that his actions will make life in his country

The song paints a narrative of a patriot, dedicated enough to give his life for his country in the earnest belief that his actions will make life in his country better. The exaggerated and romanticized version of the wife of a man like that is expected to support the same goal just as vigorously, through her sacrifices. Sending her son to serve when her husband already died that way would just be a continuation of her patriotic duty. Note that this is just my interpretation of the song and its commentary on some aspects of military culture, and not my opinion of a reasonable expectation for anyone's actual behavior.