During this phase any attacking ships will fire their guns and missiles at targets in the same sector.  Each gun fired always hits its target and inflicts one DP of damage.  A ship may fire any, all, or none of its guns in the same turn against one or more targets in the same sector, but a ship may not move and commit guns to an attack on the same turn.
 
Your battle computers provide you with two ways to target enemy ships: automatic and manual.  Automatic targeting is most useful when you have sufficient firepower to destroy all enemy ships in a sector and do not want to be bothered with tactical combat details.  Manual targeting is used when you wish to assign your attackers' guns and missiles to enemy ships in a specific manner.  Each mechanism is described below.
 
Automatic Targeting
Most of the time automatic targeting will be sufficient to carry out your attack plans.  You simply identify that attacking ships and the targeted empires. Your battle computers will automatically coordinate your attackers against all ships belonging to the targeted empire according to following criteria:
 
 

• Ships are targeted in order from fewest remaining DP to most remaining DP (in order to destroy as many individual ships as possible).
• If two ships have exactly the same remaining DP, then the one with the smaller operational rating is targeted first.
• If two ships have exactly the same OR, the the one with the smaller tonnage is targeted first.
• If two ships have exactly the same tonnage, then they are targeted alphabetically by handle.
• Missiles are targeted after all non-missiles, and in the order of their tonnage (from smallest to largest).

 
Attackers are activated in the following order:
 

• Ships with the fewest unfired guns
• Ships with the fewest available guns
• Ships with the smallest operational rating
• Ships with the fewest total guns
• Ships with the smallest tonnage
• Alphabetically thereafter

You battle computers will use your attackers' guns and missiles in an efficient manner to destroy the targets.  That is, missiles will be fired only as needed if your attackers do not possess sufficient guns to destroy all targets.  If a target ship is of an unknown foreign design, your battle computers will not know how many guns are needed to destroy that ship before the battle commences, and you will not know until the battle is over if you committed (or even possessed) enough guns to destroy it.
 
Manual Targeting
In some cases it is desirable to override your battle computers and specify exactly how you would like combat to occur.  Manual targeting allows you to do this, but requires more detailed planning on your part.  In order to use manual targeting you must explicitly identify the order in which enemy ships are to be attacked and how many guns each attacker will bring to bear against those targets.  This allows you to target enemies in any order that you like, but, unlike automatic targeting, your attackers will not use use their guns as a single efficient group.  A poorly planned manual attack can waste guns on an enemy that is already targeted.
 
Attacking Defensive Screens
Any wings that have established defensive screens around larger ships will automatically absorb damage aimed at the screened ships.  If the attacking ships possess sufficient guns to destroy the defending wings, then any excess guns will inflict damage on the original targets as intended.  Since missiles impact only a single target, no excess damage carries over to a screened target if a missile destroys a defending wing.
 
Firing Missiles
When you fire a missile all of its guns are expended against a single target and the missile is destroyed.  A missile must be unloaded from a carrier on the turn it is fired.  You can explicitly unload a missile (during the Logistics phase) before you fire it, but if you fire a loaded missile the game server conveniently issues an automatic unload command for it during combat.  If a missile is unloaded and not fired on that turn, it must be reloaded on a subsequent turn to be used (and it is also fair game for being attacked as unloaded cargo and for salvage purposes).
 Note that firing a missile is not the same as firing its carrier's guns.  That is, a loaded missile can be fired, leaving its carrier free to move to another sector in a "hit-and-run" attack.  It is possible during the Logistics phase to unload one missile, load a second missile in the same rack space, and then fire both missiles during the Combat phase.
 
Allies: Allied empires may never fire guns or missiles at each other's ships.  This includes wings forming a defensive screen, even if the screened target is not an allied ship.  That is, if an ally is defending a non-allied target, no attacking guns will be fired.
 
Abandoned Empires: Abandoned ships will always fire at non-allied ships present at friendly or allied worlds, or at ships belonging to any empire which fired on the abandoned empire during the previous turn.
 
Abandoned ships present at foreign, non-allied worlds will fire guns if they expect to destroy all foreign ships present.
 
Abandoned ships between worlds will fire upon any empire targeted by either of the above two criteria.
 
If multiple empires are targeted in the same sector, the abandoned ships will first fire upon the empire having the fewest remaining DP (or tonnage if there's a tie).