I think it isn't literally about war, but the battles we fight every day. Life is hard, "With no-one wearing their real face" - lots of lies and deceit, "shedding every value our mothers taught". But love gives our lives meaning, something to fight for. "You gave me a reason to try", "And we fought to believe the impossible" - the impossible probably being that everyone in the world would love each other. Which is easier to strive for when you got someone "by your side on the frontlines" who you can trust - "So will you please show me your real face".
I think it isn't literally about war, but the battles we fight every day. Life is hard, "With no-one wearing their real face" - lots of lies and deceit, "shedding every value our mothers taught". But love gives our lives meaning, something to fight for. "You gave me a reason to try", "And we fought to believe the impossible" - the impossible probably being that everyone in the world would love each other. Which is easier to strive for when you got someone "by your side on the frontlines" who you can trust - "So will you please show me your real face".