crouch behind cover

man behind the man behind the gun

cut behind the enemy

reconnaissance behind enemy lines

stay-behind (operations)

stay-behind ambush

stay-behind force

go behind enemy lines

moving force behind

falling behind

wake of boundary layer behind an aerofoil

cut behind defenses

fall behind time

get behind enemy lines

air box handhole cover

air cover

base cover

communications cover

construct cover

cover from view

cover plan

cover story

cover target

cover the retreat / withdrawal

crankcase handhole cover

deep-cover agent

front-line cover

operational cover

overhead cover(ing) / protection

protective cover

tactical cover and deception estimate

under cover of

body armour cover