What is a good example of a conflict that occured in ancient times that was a result of honor?
I cannot agree that the Peloponnesian Wars were fought as a matter of honor; they were rather fought for economic dominance of the area. The defeat of Persia after the last Persian war had left a power vacuum in the Aegean basin, which Athens with its powerful navy attempted to dominate. It did so by forming the Delian League, which other city-states less powerful than Athens were forced to join. Alarmed at the increasing imbalance of power, Sparta formed its own alliance, known as the Peloponnesian League. Athens ruthlessly collected tribute from its tributary states, and was at times so harsh that many revolted. When Athens attempted to force Corinth to join the Delian League, the war broke out, as Corinth had been allied with Sparta. Meetings between Spartan and Athenian officials failed to prevent the war, when Athens refused to to stop its aggression. When it appeared that war was inevitable, a Spartan representative informed the Athenian agents, "this day will be the beginning of great evil for the Greeks." He was correct.
To further answer the question presented, all wars are fought to some degree as a manner of honor on each side. Both sides appeal to the honor of their nation and of fallen comrades; soldiers are urged to fight for the honor of their homeland. but hardly any wars, if any, are fought simply over a matter of honor (unless, of course, one considers the mythical Trojan War.) Honor is often expressed as a matter of Patriotism which was the real theme of Pericles' funeral oration mentioned in the previous post:
It is true that we are called a democracy, for the administration is in the hands of the many and not of the few. But while there exists equal justice to all and alike in their private disputes, the claim of excellence is also recognized; and when a citizen is in any way distinguished, he is preferred to the public service, not as a matter of privilege, but as the reward of merit. Neither is poverty an obstacle, but a man may benefit his country whatever the obscurity of his condition. There is no exclusiveness in our public life, and in our private business we are not suspicious of one another, nor angry with our neighbor if he does what he likes; we do not put on sour looks at him which, though harmless, are not pleasant. While we are thus unconstrained in our private business, a spirit of reverence pervades our public acts; we are prevented from doing wrong by respect for the authorities and for the laws, having a particular regard to those which are ordained for the protection of the injured as well as those unwritten laws which bring upon the transgressor of them the reprobation of the general sentiment.
The above quote is from Prof. Kagan's text referenced above. Prof. Kagan describes an act of treachery by one of Pericle's kinsman, one Alciabades, as the spark that ignited the wars; but he hardly discusses "honor" as a cause.
Bottom line, Patriotism is an element in almost every war; but Patriotism is often expressed in terms of honor and glory.
This is an excellent question. Too many scholars and historians only look at economic issues when they study the origins of war. To be sure, economic reasons are important, but they are not the only ones. In the ancient world and even the modern world, I believe honor plays a very important role.
One of the greatest conflicts in the ancient world was the conflict between Sparta and Athens in the Peloponnesian war. If you think about the origins of the war and the continuation of the war, it was really a matter of pride and honor. Athens was a growing empire and so was Sparta. In the end, both wanted ascendancy. More importantly, they both knew that there would be so much destruction and loss of life, but they continued the war anyway. Honor and pride was a chief motivation. Also if you think about the length of war 431-404 B.C., it also lends support that pride and honor was paramount, because in the end there were little benefit for both sides.
If you read some of the speeches that were give in this conflict, you will clearly be able to see that honor was at stake. A great example would be Pericles's funeral oration; in fact, the word, "honor" is used seven times in the speech. Finally, for more information, take a look at Donald Kagan's interpretation of the start of the war. I will add a link.