gain intelligence

time-gain control / gain time control

Secret Intelligence Service (SIS) / Military Intelligence, Section 6 (MI6)

tactical intelligence / combat intelligence

undeclared member of the intelligence or counter-intelligence agencies

Defence intelligence of Ukraine (DIU) / Main Directorate of Intelligence of the MoD of Ukraine

gain a foothold

gain altitude

gain booty

gain files

transducer gain

gain decisive results

incremental gain

incremental power gain

gain bona fides

gain advantage over the enemy

automatic gain control

sum gain

swept gain

gain viсtory

capitalize one's gain

consolidate a gain

gain a footing

gain by force

gain concealment

gain distance from the enemy

gain information

gain possession (of)

gain scope for maneuver

gain superiority (over)

gain surprise

gain the (enemy's) rear

gain the upper hand