Krsna said, "Of generals I am Kartikeya", and also "Of generals I am Skanda, the lord of war".
Skanda, or Kartikeya, is the son of Parvati and Lord Siva. Krttikadevi, after receiving the semen of Lord Siva from Agni, also conceived a son named Skanda [Karttikeya].
Lord Siva, he is the greatest of the demigods. He was also allured by Parvati, and as a result of that attraction, this boy Karttikeya was born. That was the, what is called, conspiracy of the demigods, that unless one son is born out of the semina of Lord Siva, it is impossible to conquer the demons. So Karttikeya is considered the commander in chief of the demigods
Kartikeya is very beautiful and is situated on a peacock's back with bows and arrows and two hands. He has one head, and is considered the most beautiful personality next to Cupid. In India if a person is very beautiful, he is compared with Kartikeya.
Karttikeya is on the level of Pradyumna, another son of Lord Krsna. Karttikeya appeared as Samba, and was born in the womb of Jambavati, the most enriched wife of Krsna.
The Goddess Durga has four famous children: two daughters--the goddess of fortune, Laksmi, and the goddess of learning, Sarasvati--and two famous sons, Lord Ganesa and Lord Karttikeya (representing success and beauty). They are all considered to be demigods and goddesses
In the accounts of Lord Caitanya Mahaprabhu's dancing in front of the car during the Ratha-yatra festival, Acyutananda's name is to be found many times. It is stated that in the party of Advaita Acarya from Santipura, Acyutananda was dancing and others were singing. At that time the boy was only six years old. The Gaura-ganoddesa-dipika, compiled by Sri Kavi-karnapura, has described Acyutananda as a disciple of Gadadhara Pandita and a great and dear devotee of Lord Caitanya Mahaprabhu. According to the opinion of some, he was an incarnation of Karttikeya, the son of Lord Siva, and according to others he was formerly the gopi named Acyuta. The Gaura-ganoddesa-dipika has supported both these opinions.
During Krsna's pastime of fighting with the untouchable king who attacked the city of Mathura, Krsna did not think it wise to kill him directly with His own hand. Still the king had to be killed, and therefore Krsna decided with fine discretion that He should flee from the battlefield so that the untouchable king would chase Him. He could then lead the king to the mountain where Mucukunda was lying asleep. Mucukunda had received a benediction from Karttikeya to the effect that when he awoke from his sleep, whomever he might see would at once be burnt to ashes. Therefore Krsna thought it wise to lead the untouchable king to that cave, so that the king's presence would awaken Mucukunda and he would at once be burnt to ashes.
King Mucukunda had not slept for many, many years. He was engaged in the duty of fighting, and therefore he was very tired. So when the demigod offered a benediction, Mucukunda simply thought of sleeping. He replied as follows: "My dear Karttikeya, best of the demigods, I want to sleep now, and I want from you the following benediction. Grant me the power to burn to ashes, by my mere glance, anyone who disturbs my sleeping and awakens me untimely. Please give me this benediction." The demigod agreed and also gave him the benediction that he would be able to take complete rest. Then King Mucukunda entered the cave of the mountain. On the strength of the benediction of Karttikeya, Kalayavana was burnt into ashes simply by Mucukunda's glancing at him.
Banasura heard that the soldiers of the Yadu dynasty were attacking the whole city, tearing down various walls, gates and nearby gardens. Becoming very angry, he immediately ordered his soldiers, who were of equal caliber, to go and face them. Lord Siva was so kind to Banasura that he personally came as the commander-in-chief of the military force, assisted by his heroic sons Karttikeya and Ganapati.
During Krsna's battle with Lord Siva, Krsna's son Pradyumna was fighting fiercely with Karttikeya, the commander-in-chief of the demigods. Karttikeya was wounded, and his body was bleeding profusely. In this condition, he left the battlefield and, without fighting anymore, rode away on the back of his peacock carrier.
Bhaktivedanta Book Trust. Excerpted from various sources, including text and Purport of HDG A.C. Bhaktivedanta Swami Srila Prabhupada.
Painting is from the collection of St. Petersburg Institute of Oriental Studies.