Factional leaders might be under even more pressure to hope that a successful campaign would bolster them financially and thus allow them to increase their personal stock of weapons through the sale of captives. But it would be wrong in my view to imagine that in these situations trade off decisions about textile produciton and warfare were being made. The best apporach is to understand the politics in all their complexity, informed by knowledge of the economic consequences of military decisions. We're a long way from knowing the history of African textile production, and even the impact of the industial revolution. I'm not sure exactly what the implications of this were for the slave trade, however.
More discussion is certainly welcome.
I respond to Prof. Robbins's query about the relation of textile exports and slave exports, as mentioned by Thornton. There may be an interesting correlation suggested here between these two types of export commoditites, but I would caution against hasty conclusionss on such matters. For example, Hogendorn traces out an interesting relationship between Hausa textile production and groundnut production. The Hausa trading network quickly piced up on this preference and encouraged groundnut production, and the railheads were flooded with groundnut. So while in export terms grundnut production soared at the expense of cotton, in terms of local production, they were complementary.