Green’s Dictionary of Slang

(black) aggressive, stern; energetic, purposive.

c.1978		Bob Marley quoted in L. Gardner ‘Honoring Bob Marley’ (2000) Jahworks.org 🌐 Right now is a more militant time on earth, because it’s Jah Jah time. But me always militant, you know. Me too militant. That’s why me did things like ‘Kaya,’ to cool off the pace.
2001		(con. 1981) A. Wheatle East of Acre Lane 145: I was jus’ ramping wid you, an’ you wanna get militant.
2003		‘Smitty’ hiphopinfinity.com 🌐 Review of JEL’s 10 Seconds album [...] Moving on to ‘Dynamic Button,’ the track begins with a militant drum loop accompanied by a guitar riff and organ combination.
2017		theculturetrip.com ‘Guide to London Slang 10 Jan. 🌐 Militant – stern or difficult, like your mum.
2018-20		T. Thorne (ed.) ‘Drill Slang Glossary’ at Forensic Linguistic Databank 🌐 Militant - bold, aggressive, searching for or ready for trouble.