WOTC Green & red bar underneath soldier health? what's the red bar for?

[David]

I know that that the green bar is Will and decreases during the battle.

Underneath that there is a red bar that's hard to see, but there and of different lengths for different soldiers. Anyone know what the red bar signifys?
Is it telling me how much further my Will is likely to drop in the immediate future?

On further inspection, its full for my guys with 5 health and shorter for my other soldiers with more health down to 8 who both have the shortest red bars. It's possibly related to rank?

[David]

The soldier who got hit by the Chosen now has no red bar (and 1 health). Hmm

[Dragonixor]

Pretty sure the green bar is the "tired" meter, don't know what the other bar you're talking about is