The word ‘Antebellum’ refers to the period of time before a war (often but not always the American Civil War). In this song it’s being applied to what appears to be the innocent phase of a recently-rocky relationship. All of the related war imagery, of borders and weapons and armistice day, backed...
In the fall
We circle through the leaves
And talk about the little ones
And we smile, but never say too much
The moment always vanishing
One by one the neighbors' lights come on
Our October day is almost gone
I know the border lines we drew between us
Keep the weapons down
Keep the wounded safe;
I know our antebellum innocence
Was never meant to see the light of our armistice day
In the spring
We climbed the rolling hills
And talked about our budding plans
And we smiled
Our faces like a mirror
Showing us our secret sides
But then the fights...
The sharp words splintering the night
How I couldn't be what you'd need...
But oh how I could make you bleed...
I know the border lines we drew between us
Keep the weapons down
Keep the wounded safe;
I know our antebellum innocence
Was never meant to see the light of our armistice
But how much would I give to have it back again?
How much did we lose
To live this way?
You'll go home...I'll stay here
Seasons keep on marching
I'll stay here...you'll go home
With only strangers watching