Yes and no – it depends which time of his life you are asking about.

1. Before becoming Tirthankar – as King R̥ṣabhdev (Ādināth)

• He was the first king and law‑giver of this era.
• He organised society, taught people different professions (kalaā/vidyā), and also gave duties to kṣatriyas (warriors) for protection of the kingdom.
• So at that time, like any king, war, defence and administration were part of his worldly life.
• This is all before he took dīkṣā (renunciation).

2. After becoming Tirthankar – as Bhagwan R̥ṣabhdev Once he renounced and became a Tirthankar:

• His teaching is pure ahiṁsā (non‑violence).
• He does not promote war, killing, or hurting any living being.
• All Tirthankars teach:

- Do not harm even the smallest creature. - Anger, hatred, violence and war bind heavy karma. - The path is forgiveness, peace and self‑control.

So:

• As a king: war/defence existed as part of social order.
• As a Tirthankar: his Dharma updesh is completely against violence and war; it is based on ahiṁsā, aparigraha and self‑realisation.