advance guard
airhead
ancestor
announcer
antecedent
armed guard
avant-garde
bank guard
battle line
beachhead
bellwether
bridgehead
buccinator
bushwhacker
coast guard
cordon
cordon sanitaire
explorer
farthest outpost
first line
forebear
forefront
foregoer
forerunner
front
front line
front rank
front runner
front-runner
frontiersman
fugleman
garrison
goalie
goalkeeper
goaltender
groundbreaker
guard
guarder
guardsman
guide
harbinger
herald
inlying picket
innovation
innovator
jailer
latest fad
latest fashion
latest wrinkle
army unit
art movement
artistic movement
perspective
position
view
commander in chief
infantry
rearguard