At this point you can instruct your wings to form defensive screens around friendly larger ships in preparation for combat.  Wings that make up defensive screens will automatically receive damage from any attacking guns aimed at the defended ships.  If the defending wings are destroyed, any remaining attacking guns will strike their original targets as intended.
 
The defending wings will be activated to interpose themselves between attacker and target in the order that you specify.  Note that only wings can form defensive screens, and they can screen only friendly capital ships, gunships, orbitals, and transports.  Scouts, missiles, devices, other wings, and foreign ships cannot be so defended.  A wing can be ordered to defend only a single target per turn.
 
As a convenience, if a loaded wing is ordered to defend a larger ship, it will automatically be unloaded.
 
Allies: Allied empires can form defensive screens to defend one another's capital ships.