yadṛcchayā copapannaḿ
svarga-dvāram apāvṛtam
sukhinaḥ kṣatriyāḥ pārtha
labhante yuddham īdṛśam
Translation of Bhagavad Gita 2.32
O Partha, happy are the kshatriyas to whom such fighting opportunities come unsought, opening for them the doors of the heavenly planets.
Commentary by Sri Vishvanatha Chakravarthi Thakur of Gaudiya Sampradaya:
Moreover, more than even the victors, those who die in a just battle attain happiness. By killing Bhisma and others, you make them happier. Even without doing karma yoga, one can attain svarga through the battle, without any obstructions (apavrtam).
Commentary by Sri Ramanuja of Sri Sampradaya:
2.32 Only the fortunate Ksatriyas, i.e., the meritorious ones, gian such a war as this, which has come unsought, which is the means for the attainment of immeasurable bliss, and which gives an unobstructed pathway to heaven.
Commentary by Sri Sridhara Swami of Rudra Sampradaya:
Moreover why should there be hesitation when such great good fortune has come unsolicited. Only those who are greatly fortunate get the opportunity to fight such a battle which has manifested unsought of its own accord which is verily a direct gateway to the heavenly spheres. Another interpretation can be that only those warriors who have the opportunity to fight such a battle are happy refuting Arjuna’s earlier statement in chapter one, verse thrity-seven of how can one be happy by in slaying meaning slaying the warriors on the opposite side determined to slay him.
Commentary by Sri Madhvacharya of Brahma Sampradaya:
Sri Madhvacharya did not comment on this sloka.
Commentary by Sri Keshava Kashmiri of Kumara Sampradaya:
Normally one achieves well being after great effort whereas Arjuna is able to achieve it without any effort. This is indicated by the words yadrcchaya upapannam arrived at on its own accord. It is only the most fortunate among ksatriyas who get such unsolicited opportunities without effort. For a ksatriya who fights bravely war brings fame and opulence in this life and the next. By engaging in battle for a righteous cause exhibiting outstanding valour one’s glory is guaranteed. But what happens to those who are slain? Here Lord Krishna confirms that for the valorous who fall in battle there is an open door directly to the heavenly planets the same as for the yogis who fall short of achieving liberation.
Commentary by Sri Adi Shankaracharya of Advaita Sampradaya:
2.32 Why, again, does that battle become a duty? This is being answered (as follows) [A specific rule is more authoritative than a general rule. Non-violence is a general rule enjoined by the scriptures, but the duty of fighting is a specific rule for a Ksatriya.]: Partha, O son of Partha; are not those Ksatiryas sukhinah, happy [Happy in this world as also in the other.] who labhante, come across; a yuddham, battle; idrsam, of this kind; upapannam, which presents itself; yadrcchaya, unsought for; and which is an apavrtam, open; svarga-dvaram, gate to heaven? [Rites and duties like sacrifices etc. yield their results after the lapse of some time. But the Ksatriyas go to heaven immediatley after dying in battle, because, unlike the minds of others, their minds remaind fully engaged in their immediate duty.]
Commentary by Sri Abhinavagupta of Kaula Tantra Sampradaya:
2.32 Yadrcchaya etc. A war of this nature, because it is conducive to the heaven, should not be avoided even by other such Ksatriyas who are full of desires How much less [it is to be avoided] in the case of one to whom the science of knowledge of this nature has been taught ? This is what is intended to be conveyed [here] And the verse does not at all end with [determining how to attain] the heaven. The very thing (i.e. sin), fearing which you withdraw from the battle, will befall you branching off hundredfold. This [the Lord] says-
Sanskrit Shloka Without Transliteration Marks:
yadrcchaya copapannam
svarga-dvaram apavrtam
sukhinah ksatriyah partha
labhante yuddham idrsam
Sanskrit to English Word for Word Meanings:
yadṛcchayā — by its own accord; ca — also; upapannam — arrived at; svarga — of the heavenly planets; dvāram — door; apāvṛtam — wide open; sukhinaḥ — very happy; kṣatriyāḥ — the members of the royal order; pārtha — O son of Pṛthā; labhante — do achieve; yuddham — war; īdṛśam — like this.

It is not about war and fighting. It is about unsought opportunities for service.