back against the wall
if your back is against the wall it means you have been cornered by an unfavorable situation with no futher room to retreat and you must either fight back or die.
i didn't want to fight but that dickhead had my back against the wall so I broke a beer bottle over his head
our backs are up against the wall
When you are in a difficult situation in a lifetime with emotional distress.
We're desperate. We have no where to go. We have to fight our way out of this, confront what is in front of us. Our backs are up against the wall.