In the Iliad, the heroic code is seen through the bond of friendship, the customs of hospitality, and the concept of loyalty and courage of battle.  

The belief in hospitality customs carried great weight in the time of the Iliad. Paris kidnaps Menelaus' wife Helen while Menelaus is showing acts of kindness and hospitality to Paris. Paris commits a great offense by disregarding Menelaus' hospitality:

Paris visits Menelaus in Sparta and abducts Helen, taking her back to Troy with him, seemingly with her active cooperation. Paris also takes a large part of Menelaus’ fortune. This was a serious breach of the laws of hospitality, which held that guests and hosts owed very specific obligations to each other. In particular, the male guest was obligated to respect the property and wife of his host as he would his own.

Paris' total disrespect to Menelaus causes the Trojan War. 

During the Trojan War, various heroes showed significant courage and loyalty in battle. Achilles is a great hero in the Trojan War. However, Achilles' tragic flaw causes him to break loyalty with the Greeks. Achilles allows his pride and anger at Agamemnon to influence his decision to stop fighting the Trojans. When Achilles stops fighting, the Greeks begin losing. They suffer many losses of Greek soldiers. 

Because of an argument between Achilles and Agamemnon, Achilles decides to stop fighting the Trojans. Later on, Patroclus is killed by Hector. Achilles and Patroclus were great friends. When Hector kills Patroclus, Achilles avenges his death by killing Hector. It is the bond of friendship that causes Achilles to reenter the Trojan War. Truly, the bond of friendship was of great importance during the time of the Iliad. 

No doubt, the heroic code was an important concept during the time of the Iliad. If characters broke the heroic code, there were serious consequences. Also, it was during this time that it meant everything to a soldier to be considered heroic. Even if it meant dying, the hero lived by the honorable code. He was determined to live up to the high ethical standards associated with the heroic code.  

Describe the heroic code that is expressed in the Iliad.

The heroic code that Homer shows is one in which individuals hold specific values in the highest of regard, and are willing to wage battle to defend them.  For Homer, the hero has a clear understanding as to why he fights.  Achilles might waver in his commitment to Agamemnon, but it is clear that he fights for his reputation to be the best warrior.  His heroic code is motivated by arete, a desire to display the greatest of capacity and skill on the battlefield.  When Patrocles dies, it becomes clear that he fights for the honor of his friend.  As he makes clear to Hector, his heroic code involves little in way of negotiation and lack of commitment:  "to hack your flesh away and eat it raw.”  This code of heroism is focused in its drive.  Homer shows Achilles as embodying a heroic code where such intensity is critical to the hero's state of being.

Such a singularity in focus is seen in Hector.  He clearly understands that he fights for Troy.  The respect he affords to his family name, his father, and his fellow soldiers makes it clear that part of his heroic code is to absolutely know why he fights.  Hector does not engage in existential questioning.  Even when he knows that a part of his being yearns to be with Andromache and his son, he recognizes clearly that he has a responsibility to fight.  Certain death in the form of Achilles' wrath does not deter him.  For Hector, it is clear why he must fight.  It is understood that the purpose of being a hero is one that possesses a singularity in drive and never relent in its pursuit.  The heroic code is shown to be one in which the hero clearly understands why he fights and validates this purpose with his very being.

Consider the heroic code: explain the customs of hospitality in the Iliad as well as the concept of the loyalty and courage in the battle.

In the Iliad, the characters are to follow a heroic code. This code is a system of honor. The heroic code includes a goal. The goal of Homeric heroes is to achieve honor. Honor is essential if one wants to be a hero. That is why Achilles agrees to fight for the Greeks. He desires for his name to be honored and remembered by following generations.

No doubt, heroes value honor above life. They are willing to die for honor. They desire to be heroic in all of their endeavors. The heroes achieve honor through their engagement in in life-threatening activities (a hero cannot avoid threatening situations and maintain his honor).

The hero is determined honorable by various factors. The courage a hero displays is honorable. The difficulty of the test the hero faces determines the level of honor a hero receives. Of course, social status affects one's honor. The physical abilities a hero possesses determines one's honor. Also, the spoils of his victories earns a hero merit and honor.

While honor is the desire of the hero, there are other codes of honor that are highly revered. The laws of hospitality are part of the honorable code. When Paris visits Menelaus in Sparta, Paris breaks the heroic code or hospitality code.  

Paris visits Menelaus in Sparta and abducts Helen, taking her back to Troy with him, seemingly with her active cooperation. Paris also takes a large part of Menelaus’ fortune. This was a serious breach of the laws of hospitality, which held that guests and hosts owed very specific obligations to each other. In particular, the male guest was obligated to respect the property and wife of his host as he would his own.

Paris and his dishonorable actions cause the war between the Trojans and the Greeks. 

Sometimes the hero would allow his flaws to discredit his heroism. Achilles and his tragic flaw cause the Greeks to suffer great losses. Achilles is driven by his anger at Agamemnon for dishonoring him. Agamemnon takes Achilles' girl Briseis. This enrages Achilles. Part of being a hero is determined by the spoils of victorious battles. Achilles earned Briseis. Agamemnon insults Achilles by taking his prize. Achilles' pride and anger get in the way and cause Achilles to stop fighting: 

While the anger of Achilles is justified, his reaction reveals his tragic flaw. Achilles shows not only anger, but excessive pride. He is certainly the best warrior among the Achaeans. His strength and bravery have been proven in many battles. In a society which places the highest value on these assets, Achilles can rightly claim great honor and deference.

Truly, the honorable Achilles allows his rage and anger to interfere with his desire to be a hero:  

Achilles removes his forces from the battle; he takes his anger too far.

Following the heroic code meant being self controlled and wise. Achilles does not always follow the heroic code. 

Nevertheless, Achilles will be remembered for his heroism for he dies an honorable death while fighting for his country.