I think this song is about a soldier leaving home. The first verse is through the soldier's point of view as he is leaving home and is saying goodbye. In the second verse, I think the soldier has been seriously injured and in a critical state. His family and friends have sent him cards to wish him well. As for his ultimate fate, I'm gonna say he died as the chorus has a kind of tribute-y feel to it. "The sun will set for you" to me means that the world will honour the sacrifice this soldier made
Interesting how LP have matured, a ton of people diss them for it but c'mon I'd rather not have repeats of the rap/scream stuff, an album or two of that stuff is alright but if you're a band with something special you'll make something different yet with the same footprint that you had in early work. Chester's always had a cool voice, he gets to use it to better effect now.