The flower is a metaphor for "going home" and they can't go home till the enemy is entirely dead.
Is this a parallel for the US troops in the Middle East?
It's been ten years, in another 8 years if its still going, conceivably Father's and sons will be fighting side by side. Of course fathers and sons are already possibly fighting side by side, but for this to be a truly generational war, soldiers will have to be sent into it who had not yet been born when it started... Of course considering a 6 year old on meth with a kalashikov is pretty fucking devastating it's safe to say that the opposition has already tagged several different generations to put in towards the war effort.
I remember on Stargate Atlantis when Shepherd asked Ronin if he wanted to come back to Earth with them because they were bugging out... "No, that's impossible" He said "I refuse to leave this Galaxy until every Wraith in it is dead."