Abhimanyu was killed in a fair war if we read the scenario of whole war. He had a lot of advantage in the war. Let's read about his advantages and later we I crush the misconception regarding the war.
Advantages of Abhimanyu
- He was under the protection of a celestial armour protecting him from the attacks of warriors.
Abhimanyu is young, his prowess is great. His coat of mail is impenetrable. This one's father had been taught by me the method of wearing defensive armour. This subjugator of hostile towns assuredly knoweth the entire science (of wearing armour).
Drona Parva: Abhimanyu-badha Parva: Section XLVI
- He had a boon of being invincible in war for a day
And, indeed, your portions, ye celestials, shall fight, having made
that disposition of the forces which is known by the name of the
Chakra-vyuha. And my son shall compel all foes to retreat before him.
The boy of mighty arms having penetrated the impenetrable array, shall
range within it fearlessly and send a fourth part of the hostile
force, in course of half a day, unto the regions of the king of the
dead. Then when numberless heroes and mighty car-warriors will return
to the charge towards the close of the day, my boy of mighty arms,
shall reappear before me. And he shall beget one heroic son in his
line, who shall continue the almost extinct Bharata race.' Hearing
these words of Soma, the dwellers in heaven replied, 'So be it.' And
then all together applauded and worshipped (Soma) the king of stars.
Adi Parva: Sambhava Parva: Section LXVII
Apart from this celestial bow and chariot was also with the Abhimanyu. Now it's the time to crush misconception of his death.
Misconceptions of war.
- Abhimanyu was alone inside the chakra vyuh.
Mahabharat tells us that he had an army killed by Karna.
Karna with rage and desirous of doing good to thy son, rained showers of sharp arrows on the invincible Abhimanyu. And the heroic karna, as if in contempt of his antagonist, also pierced the latter's followers on the field of battle, with many excellent shafts of great sharpness.
Drona Parva: Abhimanyu-badha Parva: Section XXXVII
2.Group attack on Abhimanyu
Abhimanyu faced the group attack but he was not killed in a group attack. This group attack was only for disarming him. He was taking that much advantage so I think that it was not a cheating.
Hearing these words of the preceptor, Vikartana's son Karna quickly cut off, by means of his shafts, the bow of Abhimanyu, as the latter was shooting with great activity. He, of Bhoja's race (viz., Kritavarman) then slew his steeds, and Kripa slew his two Parshni charioteers. The others covered him with showers of arrows after he had been divested of his bow. Those six great car-warriors, with great speed, when speed was so necessary, ruthlessly covered that carless youth, fighting single-handed with them, with showers of arrows. Bowless and carless, with an eye, however, to his duty (as a warrior), handsome Abhimanyu, taking up a sword and a shield, jumped into the sky. Displaying great strength and great activity, and describing the tracks called Kausika and others, the son of Arjuna fiercely coursed through the sky, like the prince of winged creatures (viz., Garuda.). 'He may fall upon me sword in hand,' with such thoughts, those mighty bowmen, were on the lookout for the laches of Abhimanyu, and began to pierce him in that battle, with their gaze turned upwards. Then Drona of mighty energy, that conqueror of foes with a sharp arrow quickly cut off the hilt, decked with gems, of Abhimanyu's sword. Radha's son Karna, with sharp shafts, cut off his excellent shield. Deprived of his sword and shield thus, he came down, with sound limbs, from the welkin upon the earth. Then taking up a car-wheel, he rushed in wrath against Drona. His body bright with the dust of car-wheels, and himself holding the car-wheel in his upraised arms, Abhimanyu looked exceedingly beautiful, and imitating Vasudeva (with his discus), became awfully fierce for a while in that battle.
Drona Parva: Abhimanyu-badha Parva: Section XLVI
See, they not attacked him but only disarmed him. Group attacks we're common in the entire Mahabharat. Even Abhimanyu was a master of group attack.
And foot-soldiers and steeds and cars and elephants, belonging to thy
army and numbering by hundreds, all accomplished in smitting rushed to
the spot where Karna was frightening (his assailants). Then
Dhrishtadyumna, and Bhima and Subhadra's son, and Arjuna himself, and
Nakula, and Sahadeva, began to protect Satyaki in that battle.
Drona Parva: Dronabhisheka Parva: Section XXX
All warriors including Abhimanyu attacked Karna for protecting Satyaki.
"Sanjaya said, 'The Parthas then, headed by Bhimasena, approached that
invincible array protected by Bharadwaja's son. And Satyaki, and
Chekitana, and Dhrishtadyumna. the son of Prishata, and Kuntibhoja of
great prowess, and the mighty car-warrior Drupada. and Arjuna's son
(Abhimanyu), and Kshatradharman, and the valiant Vrihatkshatra, and
Dhrishtaketu, the ruler of the Chedis, and the twin sons of Madri,
(viz., Nakula and Sahadeva), and Ghatotkacha, and the powerful
Yudhamanyu and the unvanquished Sikhandin, and the irresistible
Uttamaujas and the mighty car-warrior Virata, and the five sons of
Draupadi,--these all excited with wrath, and the valiant son of
Sisupala, and the Kaikeyas of mighty energy, and the Srinjayas by
thousands,--these and others, accomplished in weapons and difficult of
being resisted in battle, suddenly rushed, at the head of their
respective followers, against Bharadwaja's son, from a desire of
battle. The valiant son of Bharadwaja, however, fearlessly checked all
those warriors, as soon as they came near, with a thick shower of
arrows. Like a mighty wave of waters coming against an impenetrable
hill, or the surging sea itself approaching its bank, those warriors
were pushed back by Drona. And the Pandavas, O king, afflicted by the
shafts shot from Drona's bow, were unable to stay before him.
Drona Parva: Abhimanyu-badha Parva: Section XXXIII
Abhimanyu attacked Drona with 22 warriors and Drona defeated all of them single handedly. There are many other group attacks organized by pandavas then why only Group attack on Abhimanyu is so much overrated.
3.Abhimanyu was attacked by Duhsasan's son when he was tired and unarmed.
Proceeding next towards the car of Dussasana's son, he crushed the latter's car and steeds, pressing them down into the earth. The invincible son of Dussasana, then, O sire, taking up his mace, rushed at Abhimanyu. saying, 'Wait, Wait!' Then those cousins, those two heroes, with upraised maces, began to strike each other, desirous of achieving each other's death, like three-eyed (Mahadeva) and (the Asura) Andhaka in the days of old. I ach of those chastisers of foes, struck with the other's mace-ends fell down on the earth, like two uprooted standards erected to the honour of Indra. Then Dussasana's son, that enhancer of the fame of the Kurus, rising up first, struck Abhimanyu with the mace on the crown of his head, as the latter, was on the point of rising. Stupefied with the violence of that stroke as also with the fatigue he had undergone, that slayer of hostile hosts, viz., the son of Subhadra, fell on the earth, deprived of his senses.
Drona Parva: Abhimanyu-badha Parva: Section XLVII
Read here. Abhimanyu himslef attacked Duhsasan's son with a mace and killed in a fair war. Kauravas allowed Abhimanyu to fight him with Duhsasan's son and not interfered between the war. So he was killed fairly.