The Brahmins can indeed raise war in times of emergencies or when their life is endangered or when the situation demands so.
The Shastras clearly allow it.
Manu Smriti ,Chapter 8,Sloka 348,says:
8.348. Twice-born men may take up arms when (they are) hindered (in the fulfilment of their duties, when destruction (threatens) the
twice-born castes (varna) in (evil) times,
The Yajnavalkya Smriti similarly says:
21 — 23. In cases of emergency a brahmin shall pursue a Kshatriya's
duties (administration and security) or a Vaishya's mercantile
activites. But these articles he shall not sell:– fruits, soma, silk,
medicinal creepers, curd, milk, ghee, water, sesame seeds, cooked
rice, heavy metals, acids and alkalis, honey, lac, requisites of Homa,
cloth, stone, utensils flowers, vegetables, clay, leather shoes,
deer-skin, silk, salt, meat, oil cakes, roots and perfumes.
Veda Vyasa also mentioned ‘Aapaddharmaas’ of Brahmanas rendering
Kshatriya Dharmas, Kshatriyas assuming the duties of Vaishyas and so
on. [Maha Bhagavata Purana provided escape clauses in the context of
Varnaashrama Dharma: Yasya yallakshanam drusyata tat teniva
vinirdisat/ In other words: the aspects of aptitude and practice may
be endorsed; as such the Principles are of general regulative nature
while in practice, the updated considerations of ‘Desha-Kaala-Maana
Paristhithis’ would indeed prevail]
("Apaaddharmas" mean duties during an emergency.)
The Parshara Smriti(Ch 7,Sloka 35) says:
- During a civil commotion, or in exile, or when ill, or in misfortune, the first consideration is to preserve one's life ;
practice of religion should at the time be postponed.
The above verse also can be interpreted as Shastras allowing Brahmins to take up arms when the situation is demanding so or when their lives are in danger.