Shall I militate?

When translating I came across an expression 'militate in favour'. Having dutifully looked it up in my favourite Longman's Dictionary I confirmed my hunch about its 'military' origin, however it only came with 'against' and meant 'prevent'. Other mono- and bi-ligual dictionaries concurred. Still the context clearly indicated that it should mean 'advocate, support'. I considered that the prepositional phrase must change its meaning from 'fight against' to 'fight for' and translated it accordingly.

#militateinfavour