Rubuta ci gaba ga wannan sakin layi - Brooks ya ga yaƙi a duka Yaƙin Seminole na biyu da Yaƙin Mexico-Amurka. Ya shiga cikin yakin Palo Alto da yakin Resaca de la Palma a 1846. Ya ga aiki mai yawa a yakin Monterrey, kuma ya karbi takardar shaidar zuwa kyaftin don "haƙiƙa da halayyar kirki". A shekara mai zuwa, Brooks ya kasance a Siege na Vera Cruz, yakin Cerro Gordo, Skirmish na Ocalaca, yakin Contreras, da kuma yakin Churubusco
Ka yi haƙuri. An karɓa a matsayin babban jagora a ranar 20 ga Agusta, 1847, don halin kirki da halayyar kirki a Contreras da Churubusco. Ya yi aiki a kan ma'aikatan Janar David E. Twiggs har zuwa karshen yakin.