The rules says an attacker cant loose units. Is that correct?

rules also says that the defeted player looses units due to swords icons.

question is cant attacker loose units if the attacker i the defeted player ?

The defeated player takes casualties from swords regardless of whether they were the attacker or defender.

The defender may take additional casualties due to supply limits, which the retreat rules assume will never apply to the attacker.

unless a card instructs otherwise.

 Another way an attacker can lose a unit, regardless of him winning the battle, is when the defender picks up a tides of battle card with a skull on it.

JesperAgger said:

WRONG!!!

While being always able to retreat to where your troops marched from, as an attacker, you are still at risk of loosing units if you lost the combat if your opponent (defender) has a higher total combat strength and more swords than fortifications on your house card…

As others pointed out too, if you are playing Tides of Battle, a skull icon inflicts additional casualties to an opponent, regardless of the combat outcome…

Enrick Frostbite said:

Or uses Mace Tyrell

I got a qeustion. Someone attacks Martell with Siege engine+ footman. Martell plays housecard "Arianna Martell" and loose the battle. The question is: should the attacker destroy a seige engine after coming back to area from which he marched? And why?